Patrick A. Byers Jr., 23, is accused of conspiring with several other people to kill Carl S. Lackl, who was gunned down in a drive-by shooting outside his Rosedale home in July 2007, eight days before Byers was set to go to trial in another slaying.

Lackl had identified Byers in a photo lineup as the man he saw running from an east Baltimore alley and throwing away a gun after Lackl heard gunshots in March 2006. As a result of Lackl’s statement, Byers was charged with murder in the death of Larry Haynes.

Byers is accused in a federal indictment of conspiring to kill a witness, using cell phones to arrange a murder for hire and related offenses. Attorney General Michael B. Mukasey decided to seek the federal death penalty after reviewing the case, U.S. Attorney Rod J. Rosenstein said Tuesday. Federal prosecutors filed notice Tuesday of their intent to seek capital punishment.

Among the factors that prosecutors said went into the decision were the fact that the slaying was the result of “substantial planning and premeditation,” that Byers allegedly offered to pay to have Lackl killed, and that Byers was accused in a prior homicide.

“We are disappointed that the Justice Department authorized the death penalty in this case,” said A. Eduardo Balarezo, one of Byers’ attorneys. “We do not believe the facts of the case merit such drastic punishment.”

Balarezo said Byers has “no connection” to the Lackl slaying.

Three of Byers’ alleged coconspirators — Frank K. Goodman, Steven Thompson and Michael J. Randle — face maximum penalties of life in prison, prosecutors said. Two other people allegedly involved in the conspiracy were not named in the indictment.

According to police and prosecutors, Byers plotted Lackl’s slaying from jail using a contraband cell phone, offering to pay $2,500 for the witness’ death. Lackl, a 38-year-old father of three, was lured outside his house with phone calls about a car he was trying to sell. After Lackl was killed, a coconspirator was paid for the slaying on Byers’ behalf, prosecutors said.

Lackl’s death highlighted the persistent problem of witness intimidation in Baltimore, home to a notorious street DVD called “Stop Snitching” that warned against cooperation with police.

A 2005 witness protection law includes a “hearsay exception” that allows testimony from slain or reluctant witnesses to be introduced at trial. Baltimore prosecutors planned to have Lackl testify from beyond the grave by playing his recorded statement in court, which would have been unprecedented in Maryland.

But the state ultimately dropped charges against Byers in the Haynes slaying because prosecutors felt he was more likely to be convicted in federal court.