OAKLAND --

A former BART police officer is expected to be released from jail Monday after doing his time for involuntary manslaughter for fatally shooting an unarmed passenger on New Year's Day 2009, the victim's family said Thursday.

Johannes Mehserle, 29, was sentenced to two years for shooting Oscar Grant in the back while the 22-year-old Hayward man lay face down on the platform at Oakland's Fruitvale BART Station after being pulled from a train.

Mehserle has been imprisoned in Los Angeles County Jail since being convicted July 8, and is eligible for release with credit for time served before his trial and what is known as "good time" credit: one day for every day spent behind bars.

The former officer is scheduled to be released sometime Monday, said Cephus Johnson, Grant's uncle. He said the family has been notified by state and local law-enforcement officials.

"Of course it's painful," said Johnson, 53, who lives in San Jose. "We knew it was coming one day. But as it approached, there were more sleepless nights."

He called Mehserle's release a reflection of "the total injustice that we received."

Johnson said he and other family members plan to be in Los Angeles over the weekend and on Monday to protest.

Mehserle's attorney, Michael Rains, who is appealing his client's conviction, declined to comment.

Mehserle testified he thought he was firing his stun gun instead of his pistol as he was trying to arrest Grant for allegedly resisting an officer. The case drew widespread outrage, prompting the trial to be moved from Alameda County to Los Angeles. The jury there acquitted Mehserle of murder.

Oakland police say they are prepared in the event of protests when Mehserle is freed. They said they did not expect violence, but that officers would respond based on the behavior of demonstrators.

Mayor Jean Quan said in a statement that "our thoughts are with the family and friends of Oscar Grant. ... This issue has deeply touched people in our community, and we will continue, as we have the past, to respect peaceful expression."

Cat Brooks, co-chair of the Onyx Organizing Committee, said Grant's killing and Mehserle's release "sends another message to people of color that our lives don't mean anything." Mehserle is white; Grant was black.

John Burris, an attorney representing Grant's family in a federal civil suit against individual BART officers, said Mehserle's impending release only "heightens the injustice that the family feels."