Pool Repairman Disputes Claim by Menendezes : Trial: He says brothers were at home the day before they killed their parents. They testified they were buying ammunition.

With the prosecution kicking off its rebuttal case by trying to poke holes in Lyle and Erik Menendez’s testimony, a pool repairman said he saw the brothers at their home the afternoon before they killed their parents.

In testimony at odds with the brothers’ account that they were out for the afternoon of Aug. 19, 1989--buying shotgun ammunition in fear for their lives--repairman Grant F. Walker said he saw Lyle and Erik Menendez on the tennis court behind the family’s Beverly Hills mansion.

Under a sizzling cross-examination by defense lawyers, Walker conceded that he had no written records confirming he had been at the house. But he stuck to his story, testifying repeatedly that he not only fixed spa switches that Saturday but heard one of the brothers cursing at his parents over tennis.

A few days after the killings, he heard “on the radio that a professional murder had been committed the day after I was there,” Walker said. “You don’t forget something like that.”

“It’s like the Kennedy assassination,” Walker said. “I know where I was that day too.”

Late on the night of Aug. 20, 1989, Lyle and Erik Menendez killed their parents. The brothers testified that they killed in self-defense after years of physical, emotional and sexual abuse.

Both brothers testified that on Aug. 19, they left the home in the morning and went to a gun shop in the San Fernando Valley, where they bought buckshot. Hoping to miss a family fishing trip scheduled for that night, they said, they arrived home at 4 p.m.

But Walker, 50, of Studio City testified that he saw the brothers after he arrived at the house about 2 p.m. and spent 30 to 45 minutes fixing spa switches.

Lyle Menendez, he said, was playing on the back-yard tennis court with a man who appeared to be an instructor while the parents watched. Reacting to the parents’ comments, both brothers “ranted and raved,” with Lyle Menendez hurling four-letter words at his mother, Walker said.

Earlier in the day, prosecutors called a New York bodyguard to corroborate another key date in the case. Andrew Valentine, a former police officer guarding Erik Menendez, said that on Aug. 31, 1989, he escorted the younger Menendez brother during a New York trip.

En route, Erik Menendez asked the limo driver to stop several times at computer stores for “something for his computer back home.” The Aug. 31 date is significant because witnesses disagree about when Erik Menendez returned to Beverly Hills to search the family computer to see if it contained a new will.