Montana will be following the Colorado Legislature’s lead when it tests 1,400 rape kits dating back to 1995 that weren’t submitted to the state’s crime lab by local law enforcement authorities, Attorney General Tim Fox said Thursday.

The state also will add personnel to track the kits, counsel victims and investigate when DNA from the kits result in rape suspects being identified.

“We look forward to ensuring that unsubmitted sexual assault kits in Montana are tested, to helping bring closure to a horrific event in the lives of survivors, to serving justice to perpetrators and to protecting our citizens,” Fox said.

Some of the kits, which are used to collect DNA and other evidence after a sexual assault, weren’t tested because the victims were not willing to come forward or couldn’t be found, or else because the evidence wasn’t needed.

But for one in five kits, it’s unknown why the kits weren’t submitted for testing, which Fox called troubling.

Most of the untested kits are from between 2005 to 2015, and the oldest dates back to 1995. Law enforcement agencies had not turned them over to the state crime lab in Missoula, which does all of the testing. Those submitted to the crime lab have all been tested, state officials have said.

It’s unknown how many cold or closed rape cases could be reopened as a result of the new testing, Fox said.

Last year, federal officials said 70,000 untested rape kits across the U.S. would be processed using federal funds. Other states paid for the testing themselves.

In Colorado, for example, a 2013 state law required authorities to clear the state’s backlog of untested rape kits. The state paid $3.3 million to process 3,542 kits from 300 local police agencies.

The U.S. Department of Justice gave Montana $2 million of the $38 million it awarded to state, tribal and local governments to process sexual assault kits earlier this week. Up to half of that money will go toward testing 1,100 unprocessed kits in Montana.

The FBI will test the remaining 300, Fox said.

The testing is expected to take up to 18 months.

Four people will be hired as part of the three-year project. Grant money also will be used to produce a field guide outlining policies and procedures for sexual assault investigations.

State officials plan to examine why the kits weren’t submitted at the time they were collected.