Los Angeles, California (CNN) -- A former transit police officer who was found guilty of involuntary manslaughter in the killing of an unarmed man in Oakland, California, will be sentenced Friday.
Teresa Drenick, deputy district attorney for Alameda County, said prosecutors are recommending prison time for Johannes Mehserle, who was a Bay Area Rapid Transit police officer at the time of the January 1, 2009, incident.
The defense is asking for probation.
The sentencing hearing begins at 8:30 a.m. (11:30 ET) at Los Angeles Superior Court, where the trial was moved from Alameda County to Los Angeles due to pre-trial publicity.
Mehserle, who is white, was convicted in July of shooting 22-year-old Oscar Grant, a black man, on an Oakland train platform on January 1, 2009.
The jury acquitted Mehserle of the more serious options of second-degree murder or voluntary manslaughter.
Afterward, police in downtown Oakland arrested dozens of angry protesters and issued a variety of charges, including failure to disperse, resisting arrest, burglary, vandalism and assaulting a police officer.
The city will have extra officers on hand Friday in case they are needed, said police spokeswoman Holly J. Joshi.
"We are not anticipating anything negative happening and are prepared to facilitate a peaceful protest," Joshi told CNN. "We understand that the community feels strongly about this tragic event and absolutely want to respect their right to free speech and assembly. We will not, however, tolerate any violence or destruction of businesses or personal property."
Community groups have been granted permission to rally at a plaza, an Oakland spokeswoman said.
A conviction for involuntary manslaughter normally carries a four-year sentence, but Mehserle could receive 14 years. Judge Robert Perry could add an "enhancement" that could provide for the longer sentence because a firearm was used in commission of a crime.
After the verdict, Grant family members expressed outrage at the verdict.
"My son was murdered. He was murdered. He was murdered. My son was murdered," said Grant's mother, Wanda Johnson.
Johnson and other speakers said African-Americans have too long been the victims of police abuse and a biased judicial system.
Mehserle, who was on duty when the shooting occurred, said at the trial that he intended to draw and fire his Taser rather than his gun, CNN affiliate KTVU reported.
Members of the jury, which included no African-Americans, said they were unanimous in their decision. Their finding indicates that Mehserle was criminally negligent.
Prosecutors in court filings have urged prison time.
"This case is about a law enforcement officer who abandoned all judgment and training and became part of a sweeping swell of officer aggression when he shot and killed an unarmed man," they wrote in a sentencing memorandum.
"While defendant attempted to convince the jury that the shooting was an accident, the jury found otherwise," Deputy District Attorney David R. Stein wrote.
Mehserle's attorney, Michael Rains, is asking for probation for his client.
His client did not intend to use his gun, Rains wrote in a court filing. "Rather, intending to draw his Taser, he drew his firearm accidentally, perhaps negligently."
There is "overwhelming evidence that Mehserle never intended to shoot or seriously injure Oscar Grant," the defense contends, adding that the former officer does not have a previous criminal record.
The shooting was captured on a bystander's cell-phone video camera. The video was widely circulated on the Internet and on news broadcasts, and it spurred several protests and riots in and around Oakland.
Bay Area Rapid Transit police were called to Oakland's Fruitvale station on January 1, 2009, after passengers complained about fights on a train. Officers pulled several men, including Grant, off the train when it arrived at Fruitvale.
The video showed Mehserle pulling his gun and fatally shooting Grant in the back as another officer kneeled on the unarmed man. Mehserle resigned his position a few days after the incident and was later arrested in Nevada. He was released on $3 million bail.
The former officer apologized to the public and described his memories of the moments after the shooting in a handwritten letter obtained by CNN after the verdict.
"For now, and forever, I will live, breathe, sleep, and not sleep with the memory of Mr. Grant screaming 'you shot me' and me putting my hands on the bullet wound thinking the pressure would help while I kept telling him 'you'll be okay,'" Mehserle wrote in the letter. "I tried to tell myself that maybe this shot would not be so serious, but I recall how sick I felt when Mr. Grant stopped talking, closed his eyes and seemed to change his breathing."
Mehserle's letter was dated July 4, four days before the verdict.
CNN's Phil Gast contributed to this article.