The Harvard Street Neighborhood Health Center is suing its insurance company for refusing to reimburse it for the $763,000 a one-time accountant for the center embezzled between 2003 and 2008.

The Hartford Insurance Co. told the center it won't pay the claim because the center's policies excluded theft of money by employees.

In a suit originally filed in August in Suffolk Superior Court, the health center says Nzeribe McKenzie never stole physical money and that during the period he was diverting funds, he worked as an independent contractor, providing human-resources and payroll services for the center, but was not on the health center's payroll. McKenzie used the money to buy two Lamborghinis and a penthouse condo in Cambridge and to lease a wide variety of luxury cars.

The Hartford, which is based in Connecticut, had the lawsuit transferred last week to US District Court in Boston.

In its complaint, Harvard Street says it discovered the funds were missing in 2008 when its then CEO hired McKenzie as a full-time assistant and his successor in payroll noticed "significant discrepancies" in the payroll accounts - including $700,000 in payments to two companies McKenzie set up solely to accept transfers of embezzled funds from Harvard Street. An outside auditor eventually found McKenzie had started stealing funds in 2003.

McKenzie pleaded guilty to 18 embezzlement-related counts in Suffolk Superior Court in January, 2012. He was sentenced to 2 to 3 years in state prison and ordered to repay all the funds to Harvard Street. But McKenzie, released on probation earlier this year, has yet to pay Harvard Street anything, the health center says.

The health center says that its policies with the Hartford defined money as "[c]urrency, coins and bank notes and traveler's checks, register checks and money orders held for sale to the public," but that McKenzie never walked out of the center with his pockets stuff with dollar bills or checks. Instead, the health center said, he had ADP, which processed payroll checks for it, issue checks for deposit in his company's account and transferred funds directly from Harvard Street accounts to his companies' accounts.

The Hartford has yet to file an answer to Harvard Street's complaint.