Police thus far have submitted 12 cases to the Salt Lake County district attorney's office to screen for possible charges.
Charges were denied in seven of the submissions, but prosecutors filed rape counts against five other people, three of whom are now incarcerated, and two of whom are believed to have left the country.
Police estimate they will have results from the remaining 181 kits before year's end.
The cases are "hard to work," said Sgt. Derek Christensen, who oversees the department's Special Victims Unit. Each kit that comes back with a match is "like a brand-new case again," he said, and is assigned to one of the seven officers in the unit, on top of the current caseloads. Later this month, the unit plans to add an additional detective.
Christensen said the department's policy is to contact victims face to face when there is a CODIS match, to see if they are interested in having police pursue the case. If victims have moved, officers must track them down, and they sometimes travel out-of-state.
But not every victim wants to pursue charges.
Some victims feel overwhelmed, or that they're not getting support from family members and friends, or that it is just a long process they are unwilling to endure, he said.
In four cases, victims approached by officers told them they "just want to move on with their lives, they don't want to do anything" more with the case, Christensen said.
In two other cases, police had been communicating with victims "through various means, and then for some reason they just stopped communicating with us."
Sometimes it is investigators who decide not to pursue charges.
One reason is if the DNA match corroborates information already known to law enforcement, said Sgt. Brian Shearer. For example, if the alleged rapist acknowledges having sex with an alleged victim but argues that it was consensual, a DNA match cannot determine whether that contact was consensual or nonconsensual.
In other cases, the DNA match is to a boyfriend, husband or consensual sexual partner, rather than a suspect, Shearer said.
And, in some cases, a perpetrator may have already been convicted of rape or sexual assault without having had the DNA linking him to the crime. Charges were filed and arrests made in 13 of the 767 cases even before the kits had been submitted for testing, Christensen noted.
In another case, Christensen said, a person whose DNA had a match in CODIS died before police got the results. Some matches may also stem from cases in which alleged victims have been proven to have made false reports, he added.
So far, none of the alleged perpetrators with CODIS matches has been linked to more than one of the backlog kits submitted by Salt Lake City, Christensen said, but there is an unidentified DNA profile that has shown up in multiple cases.