现场指掌纹无损转印采集系统刑侦勘查与司法鉴定应用介绍

 

现场指掌纹无损转印采集系统刑侦勘查与司法鉴定应用介绍

技术原理

核心功能与司法实战价值

1. 全客体全场景适配能力，攻克疑难指掌纹提取行业盲区

    

   系统彻底突破了传统指掌纹提取技术的客体材质、表面状态、痕迹成分限制，无论是渗透性的纸张、纸板、粗糙墙面、木质板材，还是非渗透性的高反光金属、漆面家具、玻璃、陶瓷、塑料，亦或是深色带花纹的织物、皮革、花色地砖等传统方法完全无法有效提取的复杂客体，均能实现指掌纹痕迹的高效、完整提取。尤其针对汗、油、灰、潜血混合形成的疑难指掌纹，以及现场勘查中占比极高的微弱潜隐指掌纹，具备极强的吸附与提取能力，彻底解决了刑事现场勘查中长期存在的 “看得见、取不出、比不了” 的行业痛点，将大量原本无法利用的疑难痕迹，转化为可用于同一认定、锁定嫌疑人的核心法定证据，大幅拓宽了现场指掌纹物证的可提取范围与利用率。
    
2. 完全无损提取模式，同步保全形态证据与关联生物检材

    

   系统采用纯物理转印的提取模式，全程无需使用任何化学试剂、无需对客体进行任何预处理、无需触碰破坏客体表面，不会对原始客体与痕迹造成任何污染、损伤与改变，完整保全了物证的原始状态，完全符合司法鉴定对物证提取的无损性、原始性要求，提取的痕迹具备完整的司法证据效力。在提取指掌纹形态特征的同时，专用明胶片可一并粘取痕迹中附带的皮屑、脱落细胞、微量血渍等生物检材，实现指掌纹形态证据与 DNA 生物证据的关联性同步提取、一体化保全，将痕迹的形态特征与人员身份信息直接关联，构建了 “形态特征 - 生物特征” 的完整闭环证据链，为案件侦破、证据固定、司法诉讼提供了双重核心证据支撑，彻底解决了传统提取方法中形态证据与生物检材无法同步保全、证据关联性断裂的难题。
    
3. 司法级高清数字化成像，完美适配指纹自动识别与人工比对需求

    

   系统搭载高灵敏度线阵成像器件，光学分辨率≥1000DPI，远超指纹自动识别系统（AFIS）的入库标准，可极致呈现指掌纹的纹线流向、汗孔特征、细节特征点、纹线边缘形态等微米级细节，哪怕是微弱潜隐痕迹的细微纹线特征，也能完整、清晰还原。系统采用一键式智能操作，按下按键即可自动完成扫描成像，同步输出未经任何处理的原始痕迹图像与经专业算法优化的增强图像，双轨数据源既保留了痕迹的原始司法属性，也为人工细节比对、AFIS 系统自动识别入库提供了高质量的图像基础。输出的图像可直接对接全国公安机关指纹自动识别系统，实现跨区域、跨案件的指纹串并比对，为系列案件串并、嫌疑人快速锁定提供核心技术支撑，同时原始图像可直接作为司法鉴定意见书的附件，纳入案件卷宗，具备完整的法庭举证效力。
    
4. 一体化单兵便携设计，适配全场景现场勘查实战需求

    

   设备采用高度一体化集成设计，体积小巧、重量轻盈，内置大容量可充电锂电池，支持完全脱离外接电源的野外现场独立作业，无需复杂的安装调试，开箱即可投入使用，完美适配室内封闭现场、野外偏远区域、高空作业等各类复杂现场的勘查需求，可实现单人单兵全流程操作，大幅降低了现场勘查的操作门槛。系统可配合便携仿生熏显器，预先对现场潜隐指掌纹进行无损增强，再通过转印采集系统完成提取与数字化固定，形成一套从潜隐痕迹增强、无损提取、背景剥离到数字化固定的完整现场疑难痕迹处理全流程，彻底改变了传统指掌纹提取 “现场显现 - 实验室扫描 - 后期处理” 的冗长流程，实现了现场勘查 “即提、即扫、即存、即比” 的一站式作业，大幅提升了现场勘查的工作效率与案件侦破速度。
    
5. 多语言国际化适配，满足跨境案件与国际执法协作需求

    

   系统操作界面与系统语言支持英文等多语言切换，配备完整的英文版产品说明书，电源适配器符合全球各地区的电气标准，可完美适配跨境犯罪案件勘查、国际执法协作、海外维和警务等场景的使用需求，同时成像标准、提取流程完全符合国际法庭科学指纹检验的通用规范，输出的图像与检验结果可直接用于国际刑警组织的指纹比对与跨境案件协作，具备国际通用的司法适用性。
    

刑事侦查与司法鉴定实战应用场景

1. 系列侵财案件现场疑难指掌纹提取与串并案侦查

    

   是入室盗窃、抢劫、盗抢机动车等系列侵财案件现场勘查的核心装备。此类案件中，嫌疑人遗留的指掌纹多分布于铝合金窗框、光泽漆面家具、电器外壳、玻璃门窗、玻璃瓶等光滑、高反光客体表面，传统粉末显现法极易出现纹线粘连、背景污染，光学照相法受反光、背景花纹干扰严重，无法提取到符合比对要求的清晰指纹图像，是现场勘查中的常见取证盲区。通过本系统的物理转印技术，可直接对客体表面的汗潜、油潜指掌纹进行无损粘取，彻底剥离客体反光与背景干扰，快速获取背景纯净、纹线清晰的高质量指纹图像，直接录入指纹自动识别系统进行串并比对，快速锁定嫌疑人、串并系列案件，彻底解决了传统侵财案件现场指纹提取率低、案件难以串并的侦查痛点，是当前打击系列侵财犯罪的关键技术手段。
    
2. 命案、暴力犯罪现场潜血与混合成分指掌纹提取

    

   在命案、故意伤害、抢劫杀人等暴力犯罪案件的现场勘查中，嫌疑人遗留的潜血指纹、血 - 汗 - 油混合成分指纹，多分布于深色衣物、花色床单、刀具手柄、深色木质家具等背景复杂、颜色干扰严重的客体上，传统化学显现法易造成潜血痕迹扩散、纹线破坏，光学照相法无法剥离背景花纹与颜色干扰，难以获取可用于比对的清晰纹线图像，往往成为案件侦破的瓶颈。通过本系统的物理转印技术，可将潜血、混合成分指纹从复杂背景客体上完整转移至透明明胶片，通过精密扫描成像彻底剥离背景干扰，清晰还原指纹的纹线细节与特征点，为指纹同一认定提供高质量的检材，同时同步提取指纹中的微量血渍生物检材，完成 DNA 检验与身份认定，为案件侦破提供双重核心证据，是命案现场疑难潜血指纹提取的关键技术方案。
    
3. 性侵案件接触性痕迹与生物证据同步固定

    

   在强奸、猥亵等性侵案件的现场勘查中，嫌疑人遗留的接触性掌纹、指印多分布于床单、被罩、受害人衣物、皮肤、塑料包装等柔软、渗透性、带花纹的客体上，痕迹多为微弱的油脂、皮屑接触痕迹，传统方法难以有效显现与提取，且极易破坏痕迹中附带的脱落细胞等生物检材。通过本系统的无损转印技术，可在不破坏痕迹原始状态的前提下，完整提取微弱的接触性指掌纹痕迹，同时同步粘取痕迹中附带的脱落细胞、皮屑等生物检材，实现接触痕迹形态特征与 DNA 生物证据的同步提取、关联性保全，既为嫌疑人同一认定提供了指纹形态证据，也为 DNA 身份鉴定提供了高质量的生物检材，形成了完整的证据闭环，为性侵案件的定性与嫌疑人锁定提供了关键支撑。
    
4. 实验室疑难物证终极复核与检验瓶颈突破

    

   在公安刑事技术实验室、司法鉴定机构的痕迹检验工作中，针对送检的疑难客体检材，或是经过粉末显现、502 胶熏显、化学显现等常规方法处理后，仍无法提取有效特征的疑难指掌纹检材，本系统可作为终极复核技术手段。通过物理转印技术，将检材上的潜隐痕迹从原始客体上完整分离，彻底剥离原始客体的背景、颜色、反光干扰，从常规方法失效的疑难检材上，成功提取到可用于同一认定的清晰指掌纹特征图像，突破痕迹检验瓶颈，解决大量久侦未破的积案、难案中的指纹检验难题，让原本失去检验价值的疑难物证重新发挥核心证据作用。
    
5. 犯罪现场证据链构建与犯罪行为过程重建

    

   在犯罪现场勘查中，通过系统对现场特定区域的灰尘、血迹、油脂混合痕迹进行分区提取，可精准分析不同痕迹物质的叠加顺序、空间分布关系与先后形成时序，结合现场足迹、工具痕迹等其他物证，推断嫌疑人的作案动作流程、接触顺序、活动路线，还原完整的犯罪行为过程，为案件现场重建、作案过程还原提供客观的痕迹依据。同时，系统提取的指掌纹图像可精准对应现场的原始遗留位置，与现场方位图、现场照片形成完整的空间关联，构建完整、闭环的现场证据链，提升证据体系的完整性与法庭采信度。
    
6. 重大活动安保与涉恐案件现场痕迹快速勘查

    

   适用于重大国际会议、体育赛事、节庆活动等重大活动安保，以及涉恐案件、突发公共安全事件的现场快速勘查。可对涉恐现场、可疑包裹、重点防护区域的可疑接触痕迹、指掌纹进行快速、无损提取与现场数字化固定，数分钟内即可完成痕迹的提取、扫描与入库比对，快速排查可疑人员身份、锁定涉恐嫌疑人，为重大活动安保与涉恐案件应急处置提供快速、高效的技术支撑。
    

核心技术参数

实战应用案例

1. 某市公安局刑事技术支队接连接到多起小区入室盗窃报警，犯罪嫌疑人在 2 个月内连续作案 17 起，涉案金额巨大，具备极强的反侦察意识，作案时戴手套作案，仅在少数现场的铝合金窗框、玻璃门窗、漆面衣柜上遗留了极其微弱的油潜指印。现场勘查人员采用传统粉末显现、502 胶熏显方法，均因客体高反光、痕迹微弱，无法提取到清晰的指纹纹线，光学照相也受反光干扰严重，无法获取符合 AFIS 系统入库标准的指纹图像，案件侦查陷入僵局。刑事技术人员使用本现场指掌纹无损转印采集系统，对 12 起关联案件现场的可疑痕迹区域进行了无损转印提取，通过物理粘取将微弱油潜指印从高反光客体上完整转移至明胶片，彻底剥离了客体反光与背景干扰，通过系统精密扫描成像，成功提取到 9 枚具备完整细节特征的清晰指纹图像。技术人员将提取的指纹图像录入指纹自动识别系统进行比对，成功比中了有盗窃前科的犯罪嫌疑人赵某某，最终成功抓获嫌疑人，破获了该跨区域系列入室盗窃案件，系统提取的指纹图像成为案件定罪量刑的核心法定证据。
    
2. 某县发生一起恶性杀人命案，受害人被人用刀具杀害于家中卧室，中心现场位于卧室床上，床单为深色带花纹棉质床单，作案刀具遗留于现场地面。现场勘查人员在床单、刀具手柄上发现了多处潜血指纹痕迹，但床单背景花纹复杂、颜色较深，刀具手柄为深色防滑橡胶材质，传统联苯胺显现法易造成潜血纹线扩散破坏，光学照相无法剥离背景花纹干扰，多次尝试均无法获取清晰的指纹纹线，无法完成指纹同一认定，案件侦破工作遭遇瓶颈。技术人员使用本系统，对床单、刀具手柄上的潜血指纹进行了无损转印提取，将潜血痕迹从复杂背景客体上完整转移至透明明胶片，通过系统高精度扫描成像，彻底剥离了背景花纹与颜色干扰，成功获取了 3 枚纹线清晰、特征完整的潜血指纹图像。通过指纹比对，成功比中了有暴力犯罪前科的嫌疑人王某某，结合现场提取的 DNA 证据，最终锁定并抓获了犯罪嫌疑人，成功破获该起命案。系统提取的指纹图像与同步保全的生物检材，形成了完整的证据链，在后续刑事诉讼中被人民法院全部采信，成为案件定罪量刑的关键核心证据。
    

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Application Introduction of the On-Site Fingerprint and Palm Print Non-Destructive Transfer Collection System in Criminal Investigation and Forensic Identification

Technical Principle

Core Functions and Forensic Practical Value

1. Full Object and Full Scene Adaptability, Overcoming the Industry Blind Area of Difficult Fingerprint and Palm Print Extraction

    

   The system completely breaks through the limitations of object material, surface state and trace component of traditional fingerprint and palm print extraction technology. Whether it is permeable paper, cardboard, rough wall, wood board, or non-permeable high-reflective metal, painted furniture, glass, ceramic, plastic, or dark patterned fabric, leather, colored floor tiles and other complex objects that cannot be effectively extracted by traditional methods, it can achieve efficient and complete extraction of fingerprint and palm print traces. Especially for difficult fingerprint and palm print formed by the mixture of sweat, oil, dust and occult blood, as well as the extremely weak latent fingerprint and palm print with a very high proportion in on-site investigation, it has extremely strong adsorption and extraction capacity.
    
   It completely solves the long-standing industry pain point of "visible, unextractable, uncomparable" in criminal scene investigation, converts a large number of difficult traces that could not be used originally into core legal evidence that can be used for identification and suspect locking, and greatly broadens the extractable range and utilization rate of on-site fingerprint and palm print physical evidence.
    
2. Completely Non-Destructive Extraction Mode, Simultaneously Preserving Morphological Evidence and Associated Biological Specimens

    

   The system adopts a pure physical transfer extraction mode, without using any chemical reagents, any pre-treatment of the object, or touching and damaging the object surface throughout the process. It will not cause any pollution, damage or change to the original object and traces, completely preserves the original state of the physical evidence, fully meets the non-destructive and original requirements of forensic identification for physical evidence extraction, and the extracted traces have complete judicial evidence validity.
    
   While extracting the morphological characteristics of fingerprint and palm print, the special gelatin sheet can simultaneously adhere to the biological specimens such as dander, exfoliated cells and trace blood stains attached to the traces, realizing the associated synchronous extraction and integrated preservation of fingerprint and palm print morphological evidence and DNA biological evidence, directly associating the morphological characteristics of the traces with the personnel identity information, and building a complete closed-loop evidence chain of "morphological characteristics - biological characteristics". It provides dual core evidence support for case detection, evidence fixation and judicial litigation, and completely solves the problem that morphological evidence and biological specimens cannot be preserved simultaneously and the evidence correlation is broken in traditional extraction methods.
    
3. Forensic-Grade High-Definition Digital Imaging, Perfectly Adapting to the Needs of AFIS and Manual Comparison

    

   The system is equipped with a high-sensitivity linear array imaging device, with an optical resolution of ≥1000 DPI, which far exceeds the warehousing standard of the Automated Fingerprint Identification System (AFIS). It can extremely present the micron-level details such as the ridge flow, sweat pore characteristics, detailed feature points, and ridge edge morphology of the fingerprint and palm print. Even the subtle ridge characteristics of weak latent traces can be completely and clearly restored.
    
   The system adopts one-key intelligent operation. Pressing the button can automatically complete the scanning imaging, and simultaneously output the original trace image without any processing and the enhanced image optimized by professional algorithms. The dual-track data source not only retains the original judicial attribute of the trace, but also provides a high-quality image basis for manual detail comparison and automatic identification and warehousing of the AFIS system. The output image can be directly connected to the national public security fingerprint automatic identification system, realizing cross-regional and cross-case fingerprint serial comparison, providing core technical support for serial case combination and rapid suspect locking. At the same time, the original image can be directly used as an attachment to the forensic appraisal opinion and included in the case file, with complete court proof effect.
    
4. Integrated Single-Soldier Portable Design, Adapting to the Practical Needs of Full-Scene On-Site Investigation

    

   The equipment adopts a highly integrated design, with small size and light weight. It has a built-in large-capacity rechargeable lithium battery, supports independent on-site operation in the field completely without external power supply, does not need complex installation and debugging, and can be put into use out of the box. It is perfectly suitable for the investigation needs of various complex scenes such as indoor closed scenes, remote wild areas, and high-altitude operations, and can realize the whole process operation by a single soldier, which greatly reduces the operation threshold of on-site investigation.
    
   The system can cooperate with the portable bionic fuming device to enhance the latent fingerprint and palm print on site in advance, and then complete the extraction and digital fixation through the transfer collection system, forming a complete whole process of on-site difficult trace processing from latent trace enhancement, non-destructive extraction, background stripping to digital fixation. It completely changes the lengthy process of traditional fingerprint and palm print extraction of "on-site development - laboratory scanning - post-processing", and realizes one-stop operation of "instant extraction, instant scanning, instant storage, instant comparison" in on-site investigation, which greatly improves the work efficiency of on-site investigation and the speed of case detection.
    
5. Multi-Language International Adaptation, Meeting the Needs of Cross-Border Cases and International Law Enforcement Cooperation

    

   The system operation interface and system language support multi-language switching including English, are equipped with a complete English version of the product manual, and the power adapter complies with the electrical standards of various regions around the world. It can perfectly adapt to the use needs of cross-border crime scene investigation, international law enforcement cooperation, overseas peacekeeping police and other scenarios. At the same time, the imaging standard and extraction process fully comply with the general specifications of international forensic fingerprint inspection, and the output images and inspection results can be directly used for fingerprint comparison of Interpol and cross-border case cooperation, with internationally accepted judicial applicability.
    

Practical Application Scenarios in Criminal Investigation and Forensic Identification

1. Difficult Fingerprint and Palm Print Extraction and Serial Case Investigation in Series Property Infringement Cases

    

   It is the core equipment for on-site investigation of series property infringement cases such as burglary, robbery, and motor vehicle theft and robbery. In such cases, the fingerprints and palm prints left by the suspects are mostly distributed on the surface of aluminum alloy window frames, glossy painted furniture, electrical housings, glass doors and windows, glass bottles and other smooth and high-reflective objects. The traditional powder development method is very easy to cause ridge adhesion and background pollution, and the optical photography method is seriously interfered by reflection and background patterns, so it is impossible to extract clear fingerprint images that meet the comparison requirements, which is a common evidence collection blind area in on-site investigation.
    
   Through the physical transfer technology of this system, the latent sweat and oil fingerprints and palm prints on the object surface can be non-destructively adhered directly, the object reflection and background interference can be completely stripped, high-quality fingerprint images with pure background and clear ridges can be quickly obtained, which can be directly entered into the automatic fingerprint identification system for serial comparison, quickly lock the suspect and combine series cases. It completely solves the investigation pain points of low fingerprint extraction rate and difficult case combination in traditional property infringement cases, and is a key technical means to combat series property infringement crimes at present.
    
2. Extraction of Occult Blood and Mixed Component Fingerprints in Homicide and Violent Crime Scenes

    

   In the on-site investigation of violent crime cases such as homicide, intentional injury, robbery and murder, the occult blood fingerprints and blood-sweat-oil mixed component fingerprints left by the suspects are mostly distributed on complex background and serious color interference objects such as dark clothing, colored bed sheets, knife handles, dark wooden furniture. The traditional chemical development method is easy to cause the diffusion and damage of occult blood traces, and the optical photography method cannot strip the background pattern and color interference, so it is difficult to obtain clear ridge images that can be used for comparison, which often becomes the bottleneck of case detection.
    
   Through the physical transfer technology of this system, the occult blood and mixed component fingerprints can be completely transferred from the complex background object to the transparent gelatin sheet. Through precision scanning imaging, the background interference is completely stripped, the fingerprint ridge details and feature points are clearly restored, providing high-quality specimens for fingerprint identification. At the same time, the trace blood stain biological specimens in the fingerprints are extracted synchronously to complete DNA inspection and identity identification, providing dual core evidence for case detection. It is the key technical scheme for the extraction of difficult occult blood fingerprints in homicide scenes.
    
3. Synchronous Fixation of Contact Traces and Biological Evidence in Sexual Assault Cases

    

   In the on-site investigation of sexual assault cases such as rape and indecency, the contact palm prints and fingerprints left by the suspects are mostly distributed on soft, permeable and patterned objects such as bed sheets, quilt covers, victim's clothing, skin, plastic packaging. The traces are mostly weak grease and dander contact traces, which are difficult to be effectively developed and extracted by traditional methods, and it is very easy to damage the biological specimens such as exfoliated cells attached to the traces.
    
   Through the non-destructive transfer technology of this system, the weak contact fingerprint and palm print traces can be completely extracted without damaging the original state of the traces. At the same time, the biological specimens such as exfoliated cells and dander attached to the traces can be adhered synchronously, realizing the synchronous extraction and associated preservation of contact trace morphological characteristics and DNA biological evidence. It not only provides fingerprint morphological evidence for the identification of the suspect, but also provides high-quality biological specimens for DNA identity identification, forming a complete evidence closed loop, and providing key support for the characterization of sexual assault cases and the locking of suspects.
    
4. Ultimate Review of Difficult Physical Evidence in Laboratory and Breakthrough of Inspection Bottlenecks

    

   In the trace inspection work of public security criminal technology laboratories and forensic authentication institutions, for the submitted difficult object specimens, or the difficult fingerprint and palm print specimens that still cannot extract effective features after being processed by conventional methods such as powder development, cyanoacrylate fuming, and chemical development, this system can be used as the ultimate review technical means.
    
   Through the physical transfer technology, the latent traces on the specimens are completely separated from the original object, the background, color and reflection interference of the original object are completely stripped, and clear fingerprint and palm print feature images that can be used for identification are successfully extracted from the difficult specimens where conventional methods fail. It breaks through the bottleneck of trace inspection, solves the difficult problem of fingerprint inspection in a large number of long-term unsolved cases, and makes the difficult physical evidence that originally lost the inspection value play the core evidence role again.
    
5. Construction of Crime Scene Evidence Chain and Reconstruction of Criminal Behavior Process

    

   In the crime scene investigation, through the partitioned extraction of dust, blood, grease mixed traces in specific areas of the scene by the system, the superposition sequence, spatial distribution relationship and formation time sequence of different trace substances can be accurately analyzed. Combined with other physical evidence such as on-site footprints and tool marks, the suspect's crime action process, contact sequence, activity route can be inferred, and the complete criminal behavior process can be restored, providing objective trace basis for case scene reconstruction and crime process restoration.
    
   At the same time, the fingerprint and palm print images extracted by the system can accurately correspond to the original remaining position of the scene, forming a complete spatial correlation with the scene floor plan and scene photos, building a complete and closed-loop on-site evidence chain, and improving the integrity and court admissibility of the evidence system.
    
6. Rapid Trace Investigation in Major Event Security and Anti-Terrorism Case Scenes

    

   It is suitable for the security of major events such as major international conferences, sports events, festivals, as well as the rapid on-site investigation of anti-terrorism cases and public security emergencies. It can quickly and non-destructively extract and digitally fix suspicious contact traces and fingerprints on the anti-terrorism scene, suspicious packages, and key protection areas on site. The extraction, scanning and warehousing comparison of traces can be completed within a few minutes, so as to quickly check the identity of suspicious personnel and lock anti-terrorism suspects, providing fast and efficient technical support for major event security and emergency disposal of anti-terrorism cases.
    

Core Technical Parameters

Practical Application Cases

1. The Criminal Technology Detachment of the Municipal Public Security Bureau received successive alarms of multiple residential burglaries. The suspect committed 17 consecutive crimes within 2 months, with a huge amount involved. He had a strong sense of anti-investigation, wore gloves when committing the crime, and only left extremely weak oily latent fingerprints on the aluminum alloy window frames, glass doors and windows, and painted wardrobes in a few scenes. The on-site investigators used traditional powder development and cyanoacrylate fuming methods, but failed to extract clear fingerprint ridges due to the high reflection of the object and weak traces. Optical photography was also seriously interfered by reflection, and could not obtain fingerprint images that meet the warehousing standard of the AFIS system, so the investigation of the case fell into a deadlock.
    
   The criminal technicians used this On-Site Fingerprint and Palm Print Non-Destructive Transfer Collection System to carry out non-destructive transfer and extraction of suspicious trace areas in 12 related cases. Through physical adhesion, the weak oily latent fingerprints were completely transferred from the high-reflective object to the gelatin sheet, which completely stripped the object reflection and background interference. Through the precision scanning imaging of the system, 9 clear fingerprint images with complete detailed features were successfully extracted. The technicians entered the extracted fingerprint images into the automatic fingerprint identification system for comparison, and successfully matched the suspect Zhao, who had a previous theft conviction. Finally, the suspect was successfully arrested, and the cross-regional series of burglary cases were solved. The fingerprint images extracted by the system became the core legal evidence for the conviction and sentencing of the case.
    
2. A vicious homicide case occurred in a county. The victim was killed in the bedroom of his home with a knife. The central scene was located on the bedroom bed, the bed sheet was a dark colored cotton bed sheet, and the crime knife was left on the scene floor. The on-site investigators found many occult blood fingerprint traces on the bed sheet and the knife handle, but the bed sheet has a complex background pattern and dark color, and the knife handle is made of dark non-slip rubber material. The traditional benzidine development method is easy to cause the diffusion and damage of occult blood ridges, and optical photography cannot strip the background pattern interference. Multiple attempts failed to obtain clear fingerprint ridges, and the fingerprint identification could not be completed, so the detection of the case encountered a bottleneck.
    
   The technicians used this system to carry out non-destructive transfer and extraction of the occult blood fingerprints on the bed sheet and knife handle, completely transferred the occult blood traces from the complex background object to the transparent gelatin sheet. Through the high-precision scanning imaging of the system, the background pattern and color interference were completely stripped, and 3 clear occult blood fingerprint images with clear ridges and complete features were successfully obtained. Through fingerprint comparison, the suspect Wang, who had a previous violent crime conviction, was successfully matched. Combined with the DNA evidence extracted from the scene, the suspect was finally locked and arrested, and the homicide case was successfully solved. The fingerprint images extracted by the system and the simultaneously preserved biological specimens formed a complete evidence chain, which was fully accepted by the People's Court in the subsequent criminal proceedings, and became the key core evidence for the conviction and sentencing of the case.