Aaron Hernandez, a former tight end for the New England Patriots, was found dead early Wednesday morning inside his prison cell.

It appears he committed suicide, though an investigation is currently under way to determine exactly what happened. At 3 a.m. ET, prison officials discovered Hernandez hanging by a bed sheet attached to the window in his cell, in which he was the only occupant. An hour later, he was pronounced dead at a local hospital.

Hernandez, who played for the Patriots from 2010–2012, was convicted in 2015 for the murder of Odin Lloyd, and sentenced to life in prison without parole. Last week, he was acquitted in an unrelated double murder.

The Massachusetts Department of Correction released a statement saying, "Mr. Hernandez was in a single cell in a general population unit.... Mr. Hernandez hanged himself utilizing a bed sheet that he attached to his cell window. Mr. Hernandez also attempted to block his door from the inside by jamming the door with various items.”

Officials at the Souza Baranowski Correctional Center in Shirley, Massachusetts, are investigating whether Hernandez left a note of any kind. He was not on suicide watch, which is why he was alone in his cell. Dept. of Corrections spokesman Christopher Fallon told reporters, "If he had made any kind of statement, he would have not been in that unit."

News of Hernandez's death comes on the same day that the Patriots are set to visit to the White House after their recent Super Bowl win. "We are aware of the reports, but I don't anticipate that we will be commenting today," a Patriots spokesman told ESPN.