A Baltimore drug dealer was convicted Friday of using a contraband cell phone from the city jail to orchestrate the death of witness against him, a killing that prompted authorities to call for jamming cell phone signals in prisons and a renewed attention to the risks incurred by witnesses.

Patrick A. Byers Jr., 23, now faces the possibility of the death penalty after being convicted on eight of the nine counts in a federal indictment, including murder of a witness and use of cell phones to facilitate a murder-for-hire. Byers was found innocent of one handgun charge.

His co-defendant, Frank K. Goodman, 23, was convicted on all seven counts he faced and could get a life sentence.

After a 3 1/2-week trial, jurors deliberated for a day and a half before deciding that Byers and Goodman were responsible for the death of Carl S. Lackl Jr.

Lackl, a 38-year-old single father, was slain in a drive-by shooting outside his suburban Rosedale home in July 2007. He had been lured outside the house by phone calls about a car he was trying to sell.

The case has been cited by authorities in other states who want to jam cell phone signals in prisons and jails. The federal Communications Act prevents states from using jammers or otherwise interfering with federal airwaves and makes no exception for law enforcement.

U.S. Rep. Elijah Cummings, D-Md., said the government should do everything in its power to get rid of cell phones in prisons.

"If we, in the United States, cannot block a signal effectively, then that's a problem," Cummings said.

Records from the cell phones used to call Lackl ultimately pointed back to Byers, who was in the city jail on murder charges — thanks in large part to Lackl.

Byers had been scheduled for trial a week later in a March 2006 fatal shooting. Lackl's fate was sealed, prosecutors said, the minute he identified Byers from a photo lineup as the man he saw running from the shooting scene and throwing away a gun.

Witnesses like Lackl are rare in Baltimore, said Cummings, who has who has introduced legislation that would increase federal funding for witness protection programs.

Byers' attorneys questioned Lackl's identification, noting that Lackl had come to Byers' rough east Baltimore neighborhood to buy drugs when he witnessed the slaying of Larry Haynes.

But the defense did not attempt to explain pages of phone records that showed frequent contact on the day of Lackl's murder between Byers, Goodman and the men who called Lackl, drove to his house and shot him. Byers' attorneys suggested that someone else could have been using his phone, but jurors rejected that argument.

"Obviously we're disappointed. We respect the verdict of the jury," said William B. Purpura Jr., one of Byers' attorneys.

The penalty phase, which begins April 27, "was probably the key portion of this case from the beginning," Purpura said. "It's life or death."

Neither Byers nor Goodman reacted visibly as the verdicts were read, although Goodman later buried his head in his hands as his sentencing date was discussed. Lackl's relatives sobbed, and his mother, Marge Shipley, embraced the lead prosecutor after the hearing.

"Give me a hug," she told Assistant U.S. Attorney John F. Purcell Jr.

Lackl's relatives declined to speak to reporters leaving court, and relatives and supporters of Byers and Goodman also declined to comment.

U.S. Attorney Rod J. Rosenstein, who has stepped up federal prosecutions of repeat gun offenders in Baltimore, declined to comment until the completion of the penalty phase.

"There are no winners," said Goodman's attorney, Christopher M. Davis. "Everyone's hurt in this case. It's just sad."

Even in Baltimore, home to a culture of witness intimidation documented in a notorious street DVD called "Stop Snitching," the slaying was shocking for its brazenness.

Byers worked through intermediaries to order Lackl's death and arrange to pay $2,500 for it, prosecutors said. First he called Goodman, who contracted with Marcus A. Pearson, a member of the Bloods gang.

But Pearson didn't pull the trigger. He delegated that to Johnathan R. Cornish, then 15 and eager to advance in the Bloods. Pearson drove to Lackl's house, with Cornish a passenger in a car that followed. Cornish shot Lackl four times with a .44-caliber handgun.

Ultimately, Pearson was paid $2,300 for Lackl's death. Both Pearson and Cornish pleaded guilty to their roles in Lackl's slaying and testified against Byers and Goodman. In all, six people pleaded guilty to taking part in the murder.