A U.S. Air Force court-martial convicted a serviceman of unpremeditated murder Tuesday for beating his 22-month-old son to death.

Tech. Sgt. Steven Webber, 37, Salt Lake City, was found innocent of a separate charge of aggravated assault.Maj. Edward Starr, who presided over the court-martial alone, rejected Webber's attempt to have the charge of unpremeditated murder reduced to involuntary manslaughter.

Starr set sentencing for Wednesday. Unpremeditated murder carries a maximum penalty of life in prison.

Webber, an air-traffic controller at the U.S. air base in Alconbury, 70 miles north of London, was accused of battering his son Nathan because the baby would not stop crying.

The baby was attacked on March 5 and died four days later in a hospital. According to testimony, he suffered a fractured skull, cuts and bruises - injuries so serious they could have been mistaken for a fall from an upstairs window or a car crash.

Webber testified that on the night of the attack, he went into a bedroom Nathan shared with his twin brother, Nicholas, after Nathan started crying.

"I put him on the dresser and hit him several times with my hand," said Webber, sobbing.

"All I wanted was love - that's all I wanted from the child, but he kept rejecting me," he testified. "I just lost control. After that I didn't know what happened until my wife grabbed me."

It was later determined at the hospital that the baby was suffering from appendicitis and had apparently been crying because he was in pain.

Psychiatrist James Rundell told the court that Webber had been beaten by his own father and suffered from an emotional disorder that required constant reassurance.

Webber also was under stress at the time because of a back problem and pressure from his job as an air-traffic controller, the psychiatrist said.