BOSTON (AP) — A father convicted of beating a man to death at their sons' hockey practice filed a motion Monday seeking a new trial, claiming the prosecution withheld information that could have been used to undermine a key witness.

Thomas Junta was convicted in January 2001 of involuntary manslaughter for beating Michael Costin, 40, the previous July. The men argued after Junta got angry over rough play on the ice. He was sentenced to six to 10 years in state prison.

Junta testified at his trial that he struck Costin only in self-defense. A medical examiner said Costin suffered severe brain injuries, and others said Junta pounded Costin's head and was red-faced with rage.

Defense lawyer John O'Connor said the request for a new trial is based on whether prosecutors violated a court order requiring them to present all relevant information on the medical examiner before the trial, and whether the examiner made Costin's injuries appear more vicious at trial than he did when discussing them at a professional conference in 2001.

A spokesman for the prosecutor told The Boston Herald that "we are convinced Mr. Junta received a fair trial."