A Prince George's County Circuit Court jury deliberated a little more than an hour yesterday before convicting a 22-year-old man of first-degree murder in one of a series of slayings in and around Seat Pleasant that police have attributed to warring, loosely knit gangs.

The jury rejected the testimony by defendant Curtis Windell Alston that he did not commit the slaying but confessed to it after more than 20 hours of police questioning. Taking the stand in his own defense, he told the jury that he was coaxed into confessing to the homicide by detectives who promised to move his mother to a safe location and to not charge him in the crime.

Alston also testified that Prince George's homicide detectives coached him about what to include in his statement after assuring him that they would not charge him in the Dec. 2, 1998, slaying of Arthur Carroll, 22, if he implicated another man in Carroll's death. Carroll was shot to death as he stepped into a taxicab outside his Seat Pleasant home in the 300 block of Goldleaf Avenue.

Alston testified that detectives ignored his request for an attorney and promised to move his mother to a safe location in exchange for his statement about the Carroll slaying. Alston said he feared his mother's life would be in jeopardy if he gave a statement.

According to trial testimony, authorities spent $4,500 to move Alston's mother and sister to an undisclosed location a few weeks after his Dec. 31, 1998, statement.

In her closing argument yesterday, Assistant State's Attorney Darlene Soltys scoffed at Alston's testimony that he gave a statement because he was promised that he wouldn't be charged if he implicated the other suspect, Nathaniel Damian Marr, 22. Soltys pointed out that in his statement to police, Alston admitted that he and Marr fired shots.

"Why would [detectives] have him implicate himself, if they're only going after Nathaniel Marr?" Soltys asked.

In his closing argument, Alston's attorney, Rajesh A. Kumar, accused each of the five homicide detectives who questioned Alston of lying about how the statement was obtained. "It shocks the conscience!" Kumar exclaimed. "Are they lying? Damn straight they're lying!"

Alston was convicted of first-degree murder, using a handgun in the commission of a crime of violence and first-degree assault in the shooting of the taxicab driver, Jimmy Abass. Abass who was shot in the cheek but was not seriously wounded.

Judge Richard H. Sothoron Jr. scheduled sentencing for Aug. 12. Alston faces up to life without parole for murder, plus additional time for the other charges.

Marr also is charged with killing Carroll and attempting to kill Abass. In his statement to police, Alston said he fired some bullets over the taxicab and perhaps one into the cab, while Marr fired the shots that kill Carroll.

Prosecutors contend that Marr fatally shot Carroll and that Alston wounded Abass, but Alston was charged under a statute that allows a person to be found guilty of first-degree murder if he is found to have aided and abetted a killing. Marr's trial is scheduled to begin Monday.

The Carroll slaying was one of at least 21 slayings that have occurred in and around Seat Pleasant during the last three years. Police announced in February that they had shut down the crews by making more than two dozen arrests, including arrests of seven suspects charged in eight slayings.

Soltys said in her closing that Carroll was slain in retaliation for the Nov. 29 slaying of Marr's cousin, Ronald Anthony "Cheese" Muse, 21.