Authorities said Wednesday that the death of a well-liked Davis baseball player and coach, who was punched in the face by a friend on Picnic Day and died, was a homicide.

But Yolo County prosecutors will not file charges in the killing of Scott Heinig, 22.

Though "caused by human hands," Heinig's death was "the result of a tragic set of circumstances that do not rise to the level of criminal conduct," the Yolo County District Attorney's Office said in a press release.

"We have talked to the family of Mr. Heinig, and they are behind this decision," Assistant Chief Deputy District Attorney Michael Cabral said.

The details of Heinig's death were made public for the first time Wednesday, after nearly three months of investigations by the Davis Police Department and the Yolo County Coroner's Office.

Heinig was a recent UC Davis graduate and university baseball player. He also played baseball at Davis Senior High School and was working as an assistant coach there.

On April 16, Heinig celebrated Picnic Day, the UC Davis annual open house, authorities said.

"He had been out enjoying the Picnic Day festivities and had consumed alcohol throughout the day," Lt. Paul Doroshov, Davis police spokesman, said Wednesday.

Afterward, a small number of friends gathered at a home in the 1000 block of Fifth Street, officials said.

Heinig and three or four friends were in the driveway about 8 p.m., when Heinig insisted they hit him in the face, authorities said.

A police investigation "revealed that this type of conduct was a common occurrence between Heinig and his friends," the news release said.

Heinig's friends initially refused, but then Heinig hit one of them in the face and the man punched back, it said.

The blow to Heinig's face and twisting motion of his head caused an artery in his neck to rupture, a rare injury sometimes seen in boxers, authorities said.

Heinig collapsed, hitting his head on pavement.

Lifesaving efforts at UC Davis Medical Center were unsuccessful, and Heinig died shortly after midnight.

His blood-alcohol content was measured at 0.11 five hours after the incident, authorities said. The legal level of drunkenness is 0.08.

Alcohol breaks down in the bloodstream at a rate of about 0.02 per hour, Cabral said.

Officials did not identify the man who struck Heinig but described him as a close friend who was distraught after the incident.

Scott Heinig, a UC Davis graduate and baseball player, was killed after he asked friends to slug him in the face. When they refused, he belted a pal, who hit him back. The blow broke a crucial artery.

© Copyright The Sacramento Bee. All rights reserved.

Call The Bee's Hudson Sangree, (916) 321-1191.

• Read more articles by Hudson Sangree