AUSTIN -- Newly released video shows what happened a few minutes before Austin architect, Matt Casey died in the downtown entertainment district.
Preston Sharpnack is charged with manslaughter after police say he punched Casey during Labor Day Weekend in 2012.
Sharpnack's mother says her son was defending himself and a friend but never mean to kill Casey.
"People need to know the truth. He wishes that he would've just ran. Everyone in my family would give anything to change the results," said Bettie Sharpnack, Preston's mother.
The video shows Sharpnack and his female friend, Renee Jones panhandling near 6th and Neches. Sharpnack says Casey began screaming at the couple. Jones walks toward Casey and pushes him. The two begin pushing and shoving each other. Sharpnack is seen in the background, diffusing the situation.
Sharpnack and Jones walk away in the video. Off camera, Sharpnack says Casey followed her son, and he punched Casey.
"I think in all fairness Preston had every right to defend his friend and stop Mr. Casey from following them," said Bettie Sharpnack.
Doctors say Casey didn't die from the punch but rather from the strike of his head against the ground.
Sharpnack was offered a plea agreement of eight years but lawyers say he should elect to have a jury trial.
"We don't think this should go unpunished. He has been in jail eight months now. We feel maybe this has been long enough," said Bettie Sharpnack.
Preston's trial is set for July. If convicted of manslaughter he faces two to 20 years in prison or 10 years probation.