WASHINGTON — A former U.S. government scientist accused of attempted espionage pleaded guilty to overbilling NASA and the Department of Defense more than $265,000 for contracting work, according to newly unsealed court records.

The plea in January by Stewart Nozette, 52, was made in secret because Nozette was cooperating in government corruption investigations, according to court papers unsealed last week after his arrest in an FBI sting operation.

The unsealed court documents state that Nozette admitted to overbilling NASA and the Defense Department between 2000 and 2006 to satisfy debts on real estate mortgages, auto loans and credit cards and to maintain a home swimming pool, pay medical bills and buy clothing. He pleaded guilty to tax evasion and conspiring to defraud the U.S. government. He faces sentencing Nov. 18 in that case.

Separately, Nozette was arrested last week and accused of trying to sell classified information on U.S. defense secrets to an undercover FBI agent posing as an Israeli intelligence officer. Nozette faces a court appearance in that case on Thursday on two counts of attempted espionage.

An indictment says Nozette tried to provide Israel with information about "satellites, early warning systems, means of defense or retaliation against large-scale attack, communications intelligence information and major elements of defense strategy."

A former colleague said that Nozette was primarily a defense technologist who had worked on the Reagan-era Star Wars missile shield effort formally named the Strategic Defense Initiative.

Nozette is jailed without bond in the case charging him with attempted espionage.