A Northeast Washington man pleaded guilty in D.C. Superior Court yesterday to second-degree murder in the beating death last fall of his girlfriend's 4-year-old son.

Terry T. Cain, 25, had initially been charged with second-degree murder while armed in the death of Tyrone Champ, a 47-pound boy who lapsed into a coma Oct. 7 and died three days later.

In a videotaped statement made before the boy died, Cain told police he beat the child because Tyrone was ignoring him, according to court papers filed by prosecutors.

The papers describe the beating as "particularly brutal and horrible" and say the boy's body was "literally covered with bruises." His injuries were caused by "a belt, an unknown hard object and . . . hands," and included a skull fracture, brain damage, facial wounds, internal bleeding and potentially fatal damage of the liver, intestines, kidneys and lungs, according to the court papers.

Cain, a beautician, lived with Tyrone, the boy's mother and his own four children at 1700 Maryland Ave. NE. According to papers filed by Cain's lawyer, once Cain noticed that Tyrone was unconscious and experiencing difficulty breathing, Cain attempted to resuscitate the child and called the emergency 911 telephone number.

Judge Robert S. Tignor scheduled sentencing for March 18 and ordered Cain held without bond until then.