Nanette Packard-McNeal, 46, was convicted of plotting the murder of her wealthy Newport Beach boyfriend, Bill McLaughlin, 55, to cash in on a $1 million life-insurance policy.
A jury convicted Naposki of killing McLaughlin in a separate trial and he faces a maximum sentence of life in prison.
He is expected to be sentenced in August.
Prosecutors painted Packard-McNeal as a master manipulator and 'femme fatale' who lived with McLaughlin, spending and stealing his money while cavorting with other men.
Deputy District Attorney Matt Murphy said she had to kill McLaughlin because she felt it was a matter of time before he realized she was cheating on him and stealing his money.
Packard-McNeal's defense lawyer, Mick Hill, argued she had the perfect home with McLaughlin and didn't want to ruin it.
McLaughlin had a successful medical technology business when he began dating and financially supporting Packard-McNeal.
Police say Packard-McNeal met McLaughlin after he responded to a personal ad which read: "I know how to take care of my man if he knows how to take care of me."
Naposki entered McLauglin's home on Dec. 15, 1994 and shot the him six times while he was standing in the kitchen, according to prosecutors.
McLaughlin's son heard the gunshots and called 9-1-1.
The same day, Packard-McNeal wrote a $250,000 check from McLaughlin's accounts and deposited it into her personal account, prosecutors said.
Packard-McNeal was charged in 1995 with grand theft by the Orange County District attorney's office for stealing close to $500,000 from McLaughlin before and after his murder.
She pleaded guilty and was sentenced to one year in jail. But she wasn't charged with his murder until 2009.