Brittany Murphy's former business manager says the late actress's husband Simon Monjack drained his wife's cash reserves by about 80 percent before his own death last May.

The former manager, Jeffrey Morgenroth, tells People that as a result of Monjack's alleged irresponsible spending, Murphy's 57-year-old mother Sharon now faces financial uncertainty.

"There were huge amounts of money in [Brittany's] pension plan and bank account, and all of that's gone," Morgenroth tells the magazine. "I would see it on the statements. There was money being withdrawn by Simon, hundreds of thousands."

An assistant to Morgenroth, Jeannette Bycott, says there were even troubles after Monjack's death. She says she witnessed a scene in which Monjack's mother Linda ordered Sharon Murphy to leave the couple's Beverly Hills mansion. "Linda started acting like everything belongs to her," says Bycott. "Before Sharon could say anything, Linda stated the house was now hers."

Linda Monjack denies any wrongdoing by either her or Simon and told People from her home in England, "If there is money missing I have no idea where it is."

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