New England Patriots director of player personnel Nick Caserio, who was expected to be one of the most desired candidates for general manager openings, is off the market.

Caserio signed a contract extension with the Patriots that runs through the 2020 season, according to NFL sources, a deal thought to be the single longest front-office contract in the NFL.

Including this season, years were added on to the deal, taking Caserio off the market and tying him to New England through the Bill Belichick-Tom Brady era.

While not directly addressing the extension, Belichick praised Caserio during his weekly pregame radio interview on 98.5 The Sports Hub.

"Well, I'm glad Nick is here. He's done a great job for us for a long time in a number of different roles," Belichick said. "He probably continues to do as much, probably more than, any other person in his position in the National Football League. He contributes in a lot of different way and does a great job. I'm glad we have him. I need him."

The deal has been done, in the draw for weeks now, though word of it had not gotten out until this week.

ESPN.com's Mike Reiss contributed to this report.