Suffolk County District Attorney Thomas Spota announced Friday that he won't seek a fifth term in office.

He has held the job since 2002, overseeing cases ranging from deadly DWI crashes to drug takedowns and tackling official corruption.

But last year, his office was accused of taking part in a police cover-up, and federal authorities are investigating the claim.

In a statement, he said he will retire at the end of the year:

One of Spota's highest-ranked critics, Suffolk Executive Steve Bellone, issued his own statement calling the move "long overdue."

"It would restore integrity to the District Attorney's Office," Bellone said of Spota's departure from office.

And within minutes of Spota's statement, Suffolk Police Commissioner Tim Sini announced his candidacy to fill the office — contradicting what he told legislators during his confirmation hearing last year.

Before being confirmed as the county’s top cop, he told legislators the opposite, that he would not seek the DA job.

"I've changed my mind because of the things I've learned as Suffolk police commissioner," he said Friday. "That office needs to be reformed. And I've learned a lot of specifics about the issues...and I think I'm the right man for the job."

He says he will remain commissioner while he runs for DA, a move that drew criticism from Republican Legislator Robert Trotta.

"The Republican caucus is going to be calling for his resignation," Trotta says. "We don't want him using the police commissioner's job as a pulpit, and clearly he's done that in the past."

For his part, Sini says he will have an "unconventional campaign" without fundraising.

"I'm not going to be involved in the day-to-day operations," he says. Those responsibilities will fall to former US attorney David Kelly, who Sini has appointed to help with his campaign.

About 15 other people are also expected to seek the DA job.