Michael Philbin, 21

Police say Michael Philbin was last heard from in Oshkosh, Wisconsin, around 2 a.m. on Sunday. (Oshkosh Police Dept.)

OSHKOSH, Wisc. -- A body pulled from a Wisconsin river has been identified as the son of Green Bay Packers' offensive coordinator Joe Philbin, police said Tuesday.

Michael Philbin, 21, went missing early Sunday while in Oshkosh, Wisconsin, to visit friends, police said.

No cause of death has been determined, and an autopsy was set for Tuesday, Oshkosh Police Chief Scott Greuel said at a news conference.

Packers General Manager Ted Thompson issued a statement Tuesday expressing his team's sadness.

"Our thoughts and prayers are with Joe, his wife, Diane, and the Philbin family as they cope with their loss," Thompson said. "This is an emotional and difficult time for them, and we ask that everyone respect their privacy. All of us in the Packers family share in their grief."

The body was found Monday in the Fox River after Oshkosh police put out an alert asking citizens for help in locating Philbin, a Ripon, Wisc., resident.

His last known communication was at 2 a.m. Sunday, police said.

"He talked to a friend. He didn't sound like he was under duress or he had any medical condition," police spokesman Joe Nichols told CNN affiliate WTMJ Monday. "The phone conversation ended, and that was the last time someone had voice contact."

His father, longtime college and NFL coach Joe Philbin, was preparing for the Packers' first playoff game this season against the New York Giants, set for Sunday.

Michael Philbin is the second-eldest of six children of Joe Philbin and his wife Diane, according to the Packers' website.

His father coached for 19 years at college football programs before coming to Green Bay in 2003 as an assistant offensive line coach. He became the team's offensive coordinator in 2007 and played a significant part in the Packers' league-best 15-1 regular season record this season.