Retiring Georgia Bureau of Investigation Director Vernon Keenan said the biggest challenge his replacement will face is rapid advances in technology that are making agents’ jobs more difficult.

Keenan, who worked with the bureau for nearly 40 years, announced his retirement earlier this month and worked his last day in office Monday. He has been the GBI's director since 2003 and will be replaced on an interim basis by Deputy Director Scott Dutton. Keenan's permanent replacement hasn't been announced by governor-elect Brian Kemp.

In recent years, Keenan said he’s been frustrated by shifts in technology, especially encryption, which restricts access to suspects’ cell phones and computers, locking out investigators. The issue will require constant attention to the tech market and regular upgrades in the technology available to agents, Keenan said.

“Much of the crime we’re dealing with now, there is a nexus with technology,” Keenan told The Atlanta Journal-Constitution on Friday. “It’s all types of crime. It goes from homicide to drug cases to fraud. The encryption keeps being stronger and stronger.”

In Keenan’s view, law enforcement hasn’t received much cooperation from technology companies. He isn’t alone in that view. The FBI was frustrated in 2016 by Apple’s decision to fight a court order to unlock an iPhone used by one of the shooters in a terror attack that killed 14 people in San Bernardino, Calif.

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The FBI ended up finding a way to crack the phone, without Apple's help, by using a third party to exploit a hole in the operating system's security. Soon, police across the country soon began using that method too, according to The New York Times. Apple announced in June it was closing that technological loophole, partly because of fear that criminals could also exploit it.

When a smart phone is locked, the data inside is encrypted until the pass code is typed in. Users can also download apps to enhance encryption, which privacy advocates argue has legitimate purposes for the security of law-abiding citizens, even if it complicates things for police: They may have a warrant for information stored in a device they can’t unlock.

Often, GBI agents are frustrated in their attempts to gather evidence from locked devices, Keenan said, likening it to knowing there’s a dead body in a building but not being able to open the door. The agency has been upgrading technology in recent years but still finds cases where they are locked out.

Another challenge awaiting Keenan’s replacement is a growing number of requests for help from local law agencies, Keenan said. He sees the increase as a result of a shortage of officers and experienced investigators in those smaller agencies. For example, the GBI has been getting calls for help working assault cases; in the past, it would take more serious cases, such as homicides, for a small department to ask for assistance.

If those requests for help grow, it could put even more pressure on GBI agents, who have already taken on new responsibilities in recent years. Investigating officer-involved shootings for some of the largest departments in the state has become a priority for the GBI as those cases have drawn increasing public scrutiny.

The director who will face these challenges might not be known for weeks. Gov. Nathan Deal appointed Dutton as the interim head, but the selection of a permanent leader is up to Kemp, who will be sworn in on Jan. 14. Keenan, who had been mulling retirement for years so he could spend more time with his already-retired wife, said he hasn’t heard who will be named to replace him. When he told Kemp he was leaving, Kemp didn’t ask for a recommendation, and Keenan didn’t offer one.

Whoever it turns out to be will enjoy the  groundwork laid by Keenan, according to Georgia law enforcement veterans.

“There is literally no area in our profession (that) Mr. Keenan has not touched and helped to improve,” said Frank Rotondo, executive director of the Georgia Association of Chiefs of Police. Rotondo includes technology in the areas Keenan helped the agency grow, as well as officer-involved shooting investigations, DNA testing, crime scene processing and data base creation.

Still, Keenan said there is much work to be done when his replacement takes over.

“The crime environment,” he said, “is in constant flux.”