(CNN) -- Johannes Mehserle, a former San Francisco Bay Area transit police officer, is appealing his involuntary manslaughter conviction for the killing of 22-year-old Oscar Grant in Oakland.
The move has deeply angered Grant's family, who say the appeal is an attempt for Mehserle to clear his name so that he can become a police officer again.
"I'm here to denounce his attempt to clear his record. He committed such gross negligence that he should not be allowed back on the streets to protect and serve again," said Grant's mother Wanda Johnson at a news conference Friday in Oakland.
The appeal to overturn the conviction was filed this week and argued during a court hearing on Wednesday, according to Michael Rains, Mehserle's defense attorney. The appeal questioned some of the evidence and instructions that were given to the jury at Mehserle's 2010 trial.
The three-judge panel of the First District Court of Appeal in San Francisco could make a decision on the appeal in 90 days.
Mehserle was accused of fatally shooting Grant on New Year's Day 2009 on a platform of a Bay Area Rapid Transit station. Mehserle said at the trial that he intended to draw and fire his Taser rather than his gun.
He was sentenced to two years in prison for the involuntary manslaughter conviction, but was released last year because of a California law that allowed him to reduce his sentence to nearly a year.
Grant's family members said they were also angry that they were not informed about the court hearing.
"We're angered. We are hurt," said Cephus Johnson, Grant's uncle. "We were denied our right to be at this hearing. We applied to be informed about any hearing that pertained to Johannes Mehserle. This proceeding is an example of shutting victims out of the process. The family is outraged."
This case has been controversial in California's Bay Area community for years. The 2009 shooting was captured on a bystander's cellphone video camera. The video showed Mehserle pulling his gun and fatally shooting Grant in the back as another officer knelt on the unarmed man. The video was widely circulated on the Internet and on news broadcasts, and it spurred several protests in and around Oakland.
CNN's Amanda Watts contributed to this report.