A professional tennis referee beat her elderly husband to death with a coffee cup and used the broken handle to repeatedly stab him before officiating a tennis match and getting a manicure, prosecutors said in court today.

The actions of Lois Ann Goodman showed premeditation and a lack of remorse, Deputy District Attorney Sharon Ransom said while urging a judge to keep her bail at $US1 million.

Goodman, who has refereed matches between many tennis greats, was arrested last week in New York just before she was to referee at the US Open.

After considering defense arguments, Superior Court Commissioner Mitchell Block reduced bail to $US500,000 for the 70-year-old defendant and allowed home confinement with electronic monitoring after bail is posted.

In making the ruling, Block said he considered her close ties to the community, her age and lack of a criminal record.

About two dozen supporters filled the Van Nuys courtroom as Goodman pleaded not guilty to murdering her 80-year-old husband.

Her husband, Alan Goodman, died in April. Authorities initially believed he likely fell down stairs at home while she was away, but later decided it was murder.

The prosecution asserted today the victim was struck 10 times on the head.

Defense attorney Alison Triessl has claimed her client was physically incapable of committing the crime. Triessl wrote in a previous filing that Goodman has many infirmities, including knee and shoulder replacements, and couldn't have bludgeoned her husband to death.

The filing included more than 40 letters from family, friends and colleagues who praised Goodman's generous nature and said she was never violent.

Outside court, prosecutor Ransom countered, "It was a very violent crime. The victim suffered multiple stab wounds to his head and was left there to die."

She also noted that a lot of people charged with murder are elderly and ill.

"She left him in the bed dying, went to a tennis event and had her nails done ... We see no remorse," the prosecutor said.

The Goodmans had been married nearly 50 years and have three grown daughters.

Triessl said it will be difficult for her family to raise the bail that requires 8 percent in cash and $US500,000 in collateral. She said the family is convinced her client didn't commit the crime.

- AP