The FBI is having trouble unlocking Dayton mass murderer Connor Betts’ primary smartphone — and it may take years before they crack it.

Agency officials said during a congressional hearing this week that if Betts was using a six- to eight-digit PIN, it could take months or even years to crack the code, The Hill reported Friday.

“We don’t know when we are going to get into the phone,” FBI Deputy Director David Bowdich told House Democrats during one of several briefings on the mass shooting this week, the report said.

Agents unlocked one Samsung phone belonging to Betts, CBS News reported, but the killer had “multiple phones,” the outlet reported.

Betts opened fire with an assault rifle in Dayton’s trendy Oregon District on Sunday, killing nine people in 30 seconds before he was shot dead by police.

Among the dead was his 22-year-old sister, with whom he had been socializing at a local bar less than an hour before the shooting.