A Gray man is being held on $100,000 bail, charged with fatally punching a man in Portland’s Monument Square early Sunday morning.

William Googins, 20, had his initial appearance in Cumberland County Superior Court where an arrest charge of aggravated assault was increased to manslaughter.

Googins allegedly punched Eric Benson, 24, of Westbrook one time in the head. Benson was knocked unconscious and fell to the ground.

An autopsy determined the cause of Benson’s death was blunt force trauma and the manner was homicide.

The 20-year-old was allegedly drinking in the Old Port with two friends, police said, but the friends do not appear to have been involved with the assault. Police say they are still investigating how Googins was able to be served since he is not the legal age to drink.

Defense attorney Joel Vincent was appointed to represent Googins.

Googins is being held in maximum security at Cumberland County Jail in lieu of bail.

12:59 p.m.

Prosecutors plan to upgrade the charges in connection with a fatal fight in Monument Square early Sunday morning to manslaughter.

William Googins, 20, of Gray, is charged with punching Eric Benson, 24, of Westbrook one time in the head. Benson fell to the ground and was unconscious. He was later declared dead at Maine Medical Center.

Googins turned himself in on Monday and was charged with aggravated assault.

Deputy Attorney General William Stokes said today that the charge will be upgraded to manslaughter when Googins has his initial appearance in Cumberland County Superior Court at 1 p.m. today.