The Patriots agreed to a multiyear contract extension Wednesday afternoon with director of player personnel Nick Caserio, a league source confirmed to the Globe. Exact terms of the contract are not known.

Retaining Caserio brings important continuity to the Patriots, who have suffered several coaching and personnel losses the last few years, including Matt Patricia, Brian Flores, and several assistant coaches, plus current NFL GMs Bob Quinn and Jon Robinson, and several scouts on the personnel side.

But the Patriots have been able to keep the main pieces in place — coach Bill Belichick, offensive coordinator Josh McDaniels, and now Caserio, who is de facto general manager.

A former scouting intern and position coach with the Patriots, Caserio is unique among executives in the NFL. He helps run drills at practice, speaks on the coaches’ headset from the press box during games, negotiates contracts, and runs the scouting departments and front office. Caserio has become a trusted voice in Belichick’s inner circle and an indispensable part of the operation.

Caserio’s previous contract was set to expire this spring, making him a free agent. He attempted to take a job as the Houston Texans general manager last offseason while he was still under contract, but was blocked by the Patriots.

Though Caserio was listening to offers this offseason, the Patriots badly wanted to keep him, and Caserio decided he wants to keep building on what he has helped to create over 20 years in New England.

Caserio’s return doesn’t necessarily mean Tom Brady will be back with the Patriots, per the source. Caserio could help build one last run around Brady, or help the team transition to the next era at quarterback.