The relationship between former Philadelphia Police Officer David Wade Howard and Alisa Davis produced two children, and survived other partners and seven years' separation before ending for good in 2014.

But did that final break include the killing of William Blount?

That's what a Common Pleas Court jury is being asked to answer in what a prosecutor described Tuesday as a tragedy that was "a decade in the making."

Howard, 53, is charged with murder, conspiracy, and a gun count in the Easter slaying of Blount, 49, the other man in a lovers' triangle, according to Assistant District Attorney Gail Fairman.

Fairman told the jury in her opening statement that Howard came back to Philadelphia in 2011 and found "his family invaded, taken over by Willie Blount. … He came back and he wanted his family back, he wanted Ms. Davis back."

Defense attorney Richard T. Bobbe III told the jury the prosecution will be unable to show any physical evidence proving Howard shot Blount in the head at 2:35 a.m. as he sat in his 2000 Plymouth Voyager, parked in the 3300 block of North 18th Street in Tioga, about 25 yards from Davis' house.

"Quite simply, we're here because of the lies Alisa Davis has told," Bobbe said in his opening statement. "She threw my client out there as a patsy."

Bobbe said Howard is "not only not guilty, he's innocent, and you will relish the opportunity to send him back home."

Davis, 40, was arrested in March 2015, and pleaded guilty nine months later to third-degree murder and conspiracy charges. Fairman told the jury that Davis has no agreement with the District Attorney's Office and faces a 40- to 80-year prison term when she is sentenced.

On Tuesday afternoon, Davis testified that her relationship with Blount began souring after Howard reestablished contact in 2011. By 2014, Davis said, the couple were arguing about Howard and on the verge of a breakup. She said Blount demanded the return of jewelry and the license plate to her Chevrolet Impala, which he agreed to give her while her driver's license expired.

Davis testified that she planned Blount's killing with Howard and had Howard arrive on 18th Street before she told Blount to meet her.

She said she watched as Howard approached Blount's van at an angle and fired seven or eight shots through the front windshield. She then went inside and hid, waiting for the sound of police sirens, she said.

Later on Easter, Davis continued, she called Howard to talk about their children and he "threatened me. He told me, if I say anything about this murder, he'd kill me."

In questioning Davis, Bobbe attacked her credibility, citing three early statements she gave detectives in which she denied involvement in the killing and said she did not know who did it.

Howard was living in Willow Grove in Montgomery County when he was arrested about two weeks after Davis in March 2015 and charged with witness intimidation and terroristic threats involving Blount's slaying. After Davis' guilty plea, prosecutors charged Howard as the shooter.

Howard had a prior romantic relationship that ended in violence. In May 2004, Howard, then in his 13th year with the Philadelphia police, was charged with shooting and critically wounding a Williamsport, Pa., man he caught in bed with his ex-wife in her Lycoming County apartment.

Howard was convicted of aggravated and simple assault, reckless endangerment, and terroristic threats and in 2006 was sentenced to 5½ to 15 years in prison.