DETROIT -- A Michigan State University student's Jewish religion was not a factor in an assault at an off-campus party, police said Wednesday, a day after the 19-year-old man claimed he was popped in the jaw as a victim of "religious hatred."

There is no dispute that Zach Tennen was seriously injured early Sunday. But witnesses interviewed by detectives have not confirmed Tennen's account that he was attacked after revealing he's Jewish, East Lansing police Capt. Jeff Murphy said.

Police also have no evidence that Tennen's mouth was stapled as he maintains, Murphy said.

"There's a lot more to it than what is on the surface," he told The Associated Press.

"This came out early as being reported as a hate crime. It now appears after we've talked to many people who were at this party – and most importantly two witnesses who saw the actual assault – it doesn't appear that religion was the reason he was assaulted," Murphy said.

Tennen, who is from Franklin in suburban Detroit, is recovering from jaw surgery. His father, Bruce Tennen, said the police department's latest "assertions sicken us."

Tennen was punched while in the front yard of an East Lansing home while 40 people partied in the backyard. Murphy said two people immediately helped him, put frozen vegetables on his face and got him a cab so he could go to a hospital.

The Michigan State sophomore said he was punched and had his mouth stapled after telling two men that he's Jewish. In a statement Tuesday, Tennen said, "It's shameful that in 21st century America, such religious hatred exists in our country."

Murphy said Tennen felt a wire in his mouth that he believed was a staple.

"We haven't found anything about staples. ... This was one punch to the mouth," the police captain said.

Murphy said he couldn't disclose many details about the investigation, but an 18-year-old man from Farmington Hills is a suspect. No one has been arrested.

Police are not trying to discredit Tennen, said Murphy, adding: "He definitely did not deserve to be assaulted."

Michigan State responded as soon as it heard about the attack Sunday. President Lou Anna Simon said two campus officials urged Tennen's family to report it to police.

While police might conclude anti-Semitism was not the motive, it "does not change MSU's response to a student in need or our concerns about how early reports of the incident have had a negative impact on our community," Simon said in an open letter to the area Jewish community.