The most mysterious Patriots player in recent history will remain just that.

Armond Armstead, who the Patriots signed on Feb. 1, 2013 from the Toronto Argonauts, announced his retirement on Wednesday.

The defensive lineman, 23, never played a game for the Patriots, as he dealt with injuries that prevented him from getting on the field. He suffered a heart attack in college, which led to him going undrafted and being forced to play in Canada, where he excelled before the Patriots signed him.

Almost a year ago Armstead underwent a surgery to prevent an infection, according to a team statement. He was placed on the Reserve/Non-Football Injury List on Aug. 26, 2013. At that time, he was expected to make a full recovery. He did not recover in time to join the team that season, however.