[11] Evidence can consist of DNA, saliva and fingerprints, hair, vaginal swabs, fingernail scrapings, and bed linens.
[16] Case Western Reserve University has identified the tendency of sexual offenders of being previously arrested.
[10] In order to curb and catch such offenders, the FBI created its Behavioral Science Unit in 1974.
[22] In 2014, an 18-year-old individual accused of serial rapes had used cell phone messaging apps Facebook, Kik, and Snapchat to establish a relationship with girls.
[23] A serial rapist is more prone to exhibit "criminally sophisticated behaviors" such as using a condom and gloves.
Serial rapists are more likely to control physical resistance by gagging, binding, blindfolding, and smothering.
[25] They have also been described as being able to improve their ability and expertise to commit their assault through the "study" of serial rape.
This includes rehearsal by viewing films, pornography, and reading relevant literature, using sexual fantasies, growth in knowledge in assault-related skills, learning from the examples of other serial rapists, and their own past experiences of physical or sexual abuse.
Unfortunately, the backlog of analyzing rape kits can allow the perpetrator to continue their crime before being identified with other assaults.