A Prince George's County police officer was shot to death early yesterday morning and his wife was charged with first-degree murder, police said.

Cpl. Thomas R. Smith, 31, was shot once about 12:30 a.m. yesterday during an argument at his home on Lanham Lane in Camp Springs, police spokeswoman Carol Landrum said. He was pronounced dead at the scene, police said.

Cynthia Lynn Smith, 25, who called the police to report the shooting, was arrested without incident at her home. She was being held yesterday without bond in a Prince George's County corrections center.

The couple have an 8-week-old son, police said. They had been arguing for several days, officers familiar with the couple said.

Smith was struck once in the head with a bullet from a privately owned revolver, according to the police sources.

Smith, a highly popular and commended six-year member of the force, was assigned to the Oxon Hill district in southern Prince George's County. His mother works as a secretary at that station. Smith's brother, Cpl. Teddy Smith, is assigned to the Clinton district, which includes the Lanham Lane address, and was on duty when the shooting occurred, police said.

"Tommy was one of those guys that you couldn't help but like, the all-American kind of guy," said Cpl. George Munkelwitz, who was Smith's field training officer six years ago. "He was a fine officer and will be deeply missed by all of us."

Smith was the third Prince George's County police officer to die this year; only one death, however, was duty-related.