The trial of three reserve soldiers has come to an abrupt end in Toronto after two of them pleaded guilty to charges of manslaughter and the third to a lesser charge.

The soldiers were originally charged with the second-degree murder of a 59-year-old man beaten to death in a downtown Toronto park.

But on Thursday Brian Deganis, 23, and Jeffery Hall, 23, changed their pleas, saying they were guilty of manslaughter.

Mountaz Ibrahim, 25, the third man charged, pleaded guilty to the lesser charge of being an accessory after the fact.

All three also pleaded guilty to charges of assaulting a woman who witnessed the beating.

John Rosen, the lawyer representing Hall, said the prosecution finally accepted the lesser charge of manslaughter for his client because alcohol was a factor in the attack.

"I think that what happened here was, that in an alcoholic haze, my client and Deganis misjudged entirely the situation and completely overreacted to whatever was going on," said Rosen.

Hall accepts responsibility for the attack, according to Rosen, and will take his punishment.

The victim Paul Croutch had been sleeping on a park bench in Moss Park near Sherbourne and Shuter streets in August 2005.

In court, Crown prosecutors said one of the accused was overheard saying he hated homeless people and wanted to take them on. It was after that the reservists went to the park and committed the attack.

All three men had been at a function at the nearby Moss Park Armoury.

The jury was told that Croutch was punched and kicked so hard that his body landed almost a metre behind the bench where he was sleeping.

The brutality of the killing shocked people in Toronto. It was not only the violence against a vulnerable man that caught people's attention, but also that three Canadian Forces reservists were accused of the fatal assault.

An autopsy showed Croutch suffered head injuries likely caused by punching, kicking or stomping.

Sentencing is scheduled for April 30.