Kevin Young, a key prosecution witness in the murder trials of Upper Marlboro bail bondsman Dean J. "Dino" Pantazes, was found fatally stabbed early yesterday in Northeast Washington, police said.

Young, 38, a transvestite prostitute also known as Kim Young or Mimi, was discovered about 1:40 a.m. on the front porch of a duplex in the 5500 block of Foote Street NE with a stab wound to the left side of his chest.

He was conscious when medics arrived but then stopped breathing and was pronounced dead a short time later.

Police Chief Charles H. Ramsey said D.C. homicide investigators were aware of Young's testimony against Pantazes, who was convicted of plotting the March 2000 killing of his wife, Clara. Ramsey said police also were looking at Young's criminal history.

Young, of the 2300 block of Bright Seat Road in Landover, had been convicted over the years of sexual solicitation, assault, theft and contempt of court.

He was a prosecution witness against Pantazes twice. Pantazes first was convicted in December 2000, but an appellate ruling gave him a new trial. He was convicted again in August and sentenced to two consecutive life terms.

According to Young's testimony, Pantazes hired him for sex and talked about needing to hire someone to have a woman killed. Young contacted Prince George's County police after he saw a television report about the killing.

Another prostitute, Jermel Ladonna Chambers, later admitted to shooting Clara Pantazes, 46, in her garage, saying she had been paid $5,000 by Dean Pantazes. Chambers, who also testified against Pantazes at both trials, is serving a life prison term plus 20 years.

Pantazes is appealing his latest conviction.

The place where Young was found early yesterday is just blocks from the Eastern Avenue corridor where he allegedly first met Pantazes.

A duplex resident, Samuel Covert, said he heard frantic banging on his door and found Young sitting on his front stoop with his head back, gasping for air.

"He was just moaning. He wasn't even trying to talk; he was just gasping for breath," Covert said. "After I saw the blood, that's when I called the policemen."

Covert said he returned to the porch and tried to talk to Young. "What happened? Where do you live? Are you all right?" he recalled asking. But he said Young only moaned softly.

"He had a little thunder in his voice when I first discovered him," Covert said. But later, Covert said, "that thunder in his voice had just gone into a whisper."

Staff writers Michael Amon and Jamie Stockwell contributed to this report.