LOS ANGELES, Calif. — A South Los Angeles man was convicted today of murder for the fatal 2006 shooting of two of his adult stepdaughters at a 30th birthday party for the younger victim.

Jurors found Robert Lee Phillips, 66, guilty of first-degree murder for killing 30-year-old Sabrina Taylor; second-degree murder for the death of her 33-year-old sister, Charlotte Johnson; and two counts of attempted murder involving two other people who were not wounded in the gunfire.

The panel of six men and six women also found true allegations of multiple murders and that Phillips had personally used a firearm.

Deputy District Attorney Joy Roberts told the Los Angeles Superior Court jury during the trial that the two sisters “made a fatal mistake.”

“They made someone mad,” the prosecutor said. “That final straw was the disrespect they showed to him (the defendant) in his house.”

According to the prosecutor, Phillips was escorted away from his own property on West 84th Place in an effort to cool him down following an argument over the type of music being played at Taylor’s birthday party on Sept. 2, 2006.

“He made a decision. He made a decision to kill them both,” Roberts said, telling jurors the defendant had been “stewing about what these women had been doing to him all these years.”

The prosecutor said it was “clearly proven that the defendant had the intent to kill Charlotte and Sabrina.”

Phillips fired a shot into the ground outside the gate to his house, then walked back into the yard and shot Johnson, the prosecutor said.

“That fatal bullet hit her in the head,” she said. “That was not a mistake.”

Taylor was then shot three times inside the house, including once as she cried for help. The prosecutor said the “only reasonable conclusion” was that a bullet to Johnson’s heart was fired by the defendant’s gun.

“Make him take responsibility for what he did,” Roberts told jurors.

Defense attorney Louis Sepe questioned why Phillips would want to kill his two stepdaughters, noting that his client had never lived with the two women.

“Where is the motive here?” Sepe asked jurors. “He had no intent to kill, ladies and gentlemen.”

Phillips’ attorney questioned the testimony of key prosecution witnesses. He urged jurors to find his client guilty of the lesser charge of manslaughter for Johnson’s death, but said the “ballistics aren’t there” involving the death of Taylor, who he said was “shot in the chaos and pandemonium.”

Phillips was himself shot by someone outside the party — with the prosecution arguing that he was shot after fatally shooting his stepdaughters and the defense arguing that it happened before his two stepdaughters were killed.

“Do you think that added to the passion?” Sepe asked. “It was a perfect storm, ladies and gentlemen.”

Jurors deliberated for about two and a half days before reaching their verdict.

It was the third jury to hear the case against Phillips.

The first to hear the case against him, in February 2012, acquitted Phillips of first-degree murder in Johnson’s death, but deadlocked on a second-degree murder count in that killing and a first-degree murder charge in Taylor’s death.

The second panel to hear the case deadlocked last November.

Phillips is facing life without the possibility of parole.

A date for sentencing was expected to be set this afternoon.