A Suitland man pleaded guilty yesterday to first-degree murder in the December shooting of a nanny as she cared for three children in a house near Vienna.

Earl Ray Scott, 23, had been scheduled to stand trial yesterday in Fairfax County Circuit Court in the slaying of Dena N. Perera, 22, a native of Australia. Instead, Scott pleaded guilty before Judge Robert W. Wooldridge Jr. to the murder charge and to a charge of unlawful use of a weapon.

Scott could receive 20 years to life in prison and is scheduled to be sentenced Aug. 16. He also faces a mandatory three-year sentence for the firearm conviction.

Police said Scott shot Perera six times with a 9mm semiautomatic handgun during an argument Dec. 18. The shooting occurred in the 8500 block of Electric Avenue in Tysons Woods, near Vienna, where Perera worked as a live-in nanny. Police found her body in her room in the basement. Officials said Scott had been living in the room with Perera.

Assistant Commonwealth's Attorney John Murphy said prosecutors will ask Wooldridge to impose a life sentence. "We feel this was a brutal killing, and we're going to ask the judge to use every penalty that the law allows," Murphy said.