A former Bay Area Rapid Transit officer was convicted of involuntary manslaughter Thursday for shooting an unarmed man to death at an Oakland subway station.

Johannes Mehserle, 28, shot and killed 22-year-old Oscar Grant on New Year's Day 2009 at Oakland's Fruitvale BART station platform. Mehserle claimed he inadvertently grabbed his gun instead of his Taser stun weapon.

Prosecutors asked the jury in the racially charged case to convict Mehserle, who is white, of second-degree murder for killing Grant, who is black. But the panel also had the option of convicting him of involuntary or voluntary manslaughter.

Mehserle showed no reaction as the verdict of the eight-woman, four-man jury was read. He was immediately taken into custody.

Los Angeles Superior Court Judge Robert J. Perry scheduled sentencing for Aug. 6. An involuntary manslaughter charge normally carries a prison sentence of two to four years, but the jury also found true a sentencing- enhancement that Mehserle personally used a handgun in the commission of a crime.

The courtroom audience remained silent when the verdict was read. Perry warned members of the audience before the verdict was announced that he would not tolerate any outbursts.

Members of Grant's family sat quietly, and bowed their heads in prayer before the jury was led into the courtroom.

The shooting of Grant was caught on video and sparked angry protests and outrage in the community, prompting the trial to be moved from Alameda County to Los Angeles.

There were no black jurors on the panel that convicted Mehserle.

Outside the courthouse, an attorney for the Grant family said the conviction was better than nothing, but the family was angered that Mehserle was not convicted of a more severe charge of second-degree murder.

"This is not an involuntary manslaughter case,'' attorney John Burris told a throng of reporters outside the Criminal Courts Building. "This is a true compromise verdict that does not truly and accurately reflect the facts, and we are extraordinarily disappointed at that. We do believe that this was a murder case, a second-degree murder, and we are surprised that the jury came back as quickly as they did and seemed to be very dismissive of the murder charge and the voluntary manslaughter.

"Now, of course, we feel that the involuntary manslaughter conviction is better than no conviction at all,'' he said. "We do recognize and appreciate that there probably is some historical significance that I -- in my long history, being involved in police matters since 1979 and well over 30 homicides involving the police -- I've never had a case where an officer was convicted of any crime against an African-American male.

"So in that sense, it's a small victory, but it does not in and of itself fairly and accurately represent that the system works,'' Burris said. "But it cannot work in a situation when a person is killed with his hands behind his back and an officer over him claiming that he's seen something and that becomes an involuntary manslaughter, particularly when there was no statements made ever within the first several days of this shooting where the officer claims that in fact it was a mistake. In fact, all of his conduct at the outset clearly indicated that he thought he was intending to do what he did.''

Mehserle testified during the roughly three-week trial that the shooting was accidental and that he meant to use a stun gun instead of his service handgun while trying to subdue Grant.

But Alameda County Deputy District Attorney David R. Stein told jurors in his closing argument that the defendant "lost all control'' when he intentionally shot Grant because the victim was resisting arrest.

The shooting is "what happens when a police officer acts out of the desire to punish people,'' Stein said. "He let his emotions dictate his actions ... The defendant's desire to mistreat Mr. Grant ... resulted in the death of an innocent person.''

In his summation, defense attorney Michael L. Rains said the case against Mehserle was riddled with reasonable doubt.

"There's nothing that suggests an intent to kill -- nothing,'' Mehserle's lawyer said.

Rains said his client "wasn't trying to kill Mr. Grant ... he was trying to Tase Mr. Grant.''

Referring to the racial dimension of the closely watched case, Rains urged jurors to resist using their decision to "address social injustice ... or render a verdict as some sort of commentary'' on the relationship between the police and minorities.

Last week, the judge rejected a prosecution request that jurors be allowed to consider first-degree murder against Mehserle, saying there wasn't enough evidence to show the shooting of Grant was premeditated.

Jurors deliberated for about 2 1/2 hours last Friday, but after a day off for the Fourth of July holiday on Monday, the panel had another day off on Tuesday due to a sick juror.

On Wednesday, an alternate juror had to be seated to replace a juror who was excused due to a pre-planned vacation. The reconstituted panel began its deliberations from scratch Wednesday morning, but only deliberated until about noon before resuming at 9 a.m. Thursday.

Overall, the reconstituted panel deliberated for about six hours.

Grant's uncle, Cephus "Bobby'' Johnson, told reporters the family was "slapped in the face by this system that denied us true justice.''

"It is our believe that Mehserle committed murder,'' he said. "How the jury saw this, came to their decision, is not understandable to the family.''

Johnson said the family was looking forward to speaking to the judge at the sentencing hearing, when they planned to urge Perry to give Mehserle a lengthy prison term.

"We do not want this murderer to be released to go home and eat dinner and be hired by another police department somewhere in the country,'' Johnson said.

Police in the Oakland area were reportedly preparing for possible violent outbreaks in response to the verdict.

Johnson said people "will express their feelings in ways that are appropriate to them.''

Burris urged people not to react violently to the verdict.

"We do not want anyone to be injured, to be hurt, property destroyed or lives lost as a consequence of this verdict,'' he said. "One death is enough.''

Gov. Arnold Schwarzenegger issued a statement also urging people not to react violently.

"I encourage Californians to remain calm in light of the verdict and
not to resort to violence,'' Schwarzenegger said. "I have spoken to Oakland Mayor Ron Dellums and have assured him we are well prepared to assist in maintaining order.''