After witnessing a fatal shooting at his friend's house last year, Karl Laughlin said he found himself driving across town with his friend's wife's body and the victim's sleeping child.

During his testimony yesterday at the friend's homicide trial, a defense lawyer asked why Mr. Laughlin didn't pull over and report the crime to the police rather than help defendant Henry Lanz in the cover up.

"I wasn't thinking right . . . He told me he was going to kill me. It wouldn't look very good if I got pulled over. I've got a dead woman in the car. I got her child, too. I got an active warrant," said Mr. Laughlin, 50.

Mr. Laughlin, who had been hiding out at Mr. Lanz's home in Scott to escape apprehension on an assault charge, told jurors fear motivated him. He agreed to drive Paula Lanz's Kia minivan, with her body in it, across town where Mr. Lanz and Mr. Laughlin left the Lanz's two young daughters with a baby sitter. He later agreed at Mr. Lanz's direction to drive the same minivan out of town and dispose of the body. After a multistate trek with the corpse on board, Mr. Laughlin said, he burned the car in Nashville, Tenn., and was arrested after he hitchhiked home to Pennsylvania.

Mr. Lanz, 42, opted for a jury trial on charges of homicide, conspiracy, hindering apprehension or prosecution, false reports to law enforcement, abuse of a corpse and tampering with evidence.

Ms. Lanz, 39, died of gunshot wounds to the head.

The prosecution put its key witness on the stand yesterday in an attempt to show that Mr. Lanz killed his estranged wife and orchestrated Mr. Laughlin's actions. Mr. Laughlin faces a separate trial for conspiring and burning the body, but the Allegheny County district attorney agreed not to prosecute him for homicide.

The bespectacled Mr. Laughlin, dressed in a suit and tie with long hair parted and held back in a ponytail, said he met Mr. Lanz when they worked together at a moving company and regularly heard him complain about his estranged wife. Once, he told jurors, Mr. Lanz handed him a bag of pills and asked "Would any of them kill my wife?" Another time Mr. Lanz pulled out a wad of bills and offered Mr. Laughlin's girlfriend's daughter about $1,000 to beat Ms. Lanz with a baseball bat.

The day Ms. Lanz died, Mr. Laughlin said he had been staying at the Lanzes' new house in Scott, hiding out while he was wanted on charges of assaulting his girlfriend.

He said he was on the main floor of the house when Ms. Lanz came over to pick up their 5- and 2-year-old daughters on Jan. 28, 2007. The on-again-off-again couple, who were separated at the tiem, "exchanged pleasantries" and the girls hugged and kissed their mother. Mr. and Ms. Lanz then went to the basement and got into a shouting match, he said, because Paula wanted Henry to move out.

He testified that he heard them yell profanities at each other "and then I heard a scream and then I heard a popping sound." He then went downstairs, as Ms. Lanz staggered backward into a squatting position in the corner. He saw blood gushing from a wound where Ms. Lanz was holding her hand to her cheek.

"I see him raise his hand and I see him shoot his wife," he said, describing the weapon as a chrome semiautomatic pistol.

He said Mr. Lanz then told him, "I'll kill you. I'll kill everybody involved with this. You're gonna help me get away with this."

Mr. Lanz rolled up the body in a green blanket, sealed it with duct tape and got Mr. Laughlin to help him put it in her van.

Several hours later they drove across town to her house in two cars, each with one of the daughters.

The two men communicated by cell phone while Mr. Laughlin said he drove through West Virginia, Virginia, North Carolina, Georgia and Tennessee.

Two days into the journey, Mr. Lanz agreed to wire his friend money at a truck stop in Commerce, Ga. The jury saw a copy of the wire transfer form for $140 in which Mr. Laughlin said Mr. Lanz used a fake name, Steve Thomas. They also viewed a surveillance video from a Kmart in Bridgeville in which a man resembling Mr. Lanz fills out the wire transfer form while two little girls, who appear to be with him, run around the store, playing.

Mr. Laughlin said he began to suspect Mr. Lanz was setting him up and "guilt was just eating at me," so he headed north again, planning to dump the car and the body in Mr. Lanz's driveway.

When he saw police near the minivan in Tennessee, he abandoned it. He returned later, parked it in a remote lot and set it on fire, he said, before hitch hiking north again on "back country roads."

Police arrested him upon his return and Nashville officials had already processed the crime scene he left behind. He gave police a statement about the homicide several months after his arrest.

Several other prosecution witnesses also testified yesterday that prior to the homicide, Mr. Lanz had wanted to kill his wife.

Chris Coneway, who had worked with him at the moving company, told jurors Mr. Lanz asked him "if I could get him a small caliber handgun" and "he asked if I know anybody that could take care of his wife. "He said he had $983 he would pay someone to take care of his wife."

The prosecution and defense both rested this morning.

Allegheny County Judge Jeffrey A. Manning dismissed the jury because Friday is scheduled for pre-trial conferences and Monday is a holiday.

The attorneys will present closing arguments Tuesday.