The Sheriff’s Identification Unit (SIU) performs an integral role in contributing to the public safety of Santa Clara County citizens by providing fingerprint comparison and identification services to the Santa Clara County Sheriff’s Office, as well as Police Departments and other Law Enforcement Agencies across the County. Notable end users of SIU's services include the District Attorney's Office, Public Defender's Office, and the Office of the Medical Examiner – Coroner.
SIU's primary responsibility is the analysis, comparison, and evaluation of finger and palm prints obtained from crime scenes – known as “latent prints” – for the purposes of identifying the source of them. SIU processes 1,000 latent print cases per year on average, developing investigative leads for Detectives and Attorneys. SIU staff provide their findings to customer agencies and divisions via reports, and are sometimes required to testify to these findings in court.
SIU also performs the core function of confirming the identity of arrestees for all policing agencies in Santa Clara County. At the time of criminal arrest, an arrestee's finger and palm prints are taken electronically on machines called “Live Scans.” These arrest prints are known as “tenprints”. Tenprints are searched and stored in the Santa Clara County Automated Fingerprint Identification System (AFIS) database. SIU is responsible for the searching, accurate identification, and database maintenance of AFIS for all tenprints collected within Santa Clara County. Santa Clara County's AFIS receives over 60,000 criminal bookings per year.
Another key service that SIU provides to the community is the identification, via fingerprints, of deceased persons for the Santa Clara County Office of the Medical Examiner – Coroner. This crucial function is particularly important for decedents whom are indigent, have no available next of kin, are homicide victims, or who are otherwise not viewable due to trauma. SIU identifies, on average, more than 600 decedents for the Medical Examiner - Coroner every year; around 1,000 decedents in 2020 due to the COVID-19 pandemic.
Additionally, SIU examiners are sometimes called upon to process evidence for latent prints using chemical development and enhancement techniques. SIU examiners may also attend crime scenes when required to assist in collecting and preserving latent prints.
SIU examiners possess a wealth of specialized knowledge, training, and experience in order to perform these vital functions. The citizens of Santa Clara County can expect an exceptionally high standard of work product from SIU and can be confident in the reliability and effectiveness of their services. The unit has been accredited to an international standard (ISO 17020) since 2018, and requires its examiners to obtain individual certification from the International Association for Identification as Certified Latent Print Examiners (CLPEs) as part of their in-house training. SIU's staff is actively involved in the scientific community - serving on boards, reading and writing peer reviewed articles, and lecturing on fingerprint and latent related topics. SIU members are seen as industry leaders and are well respected in their field.