Roland Arnall, founder of defunct subprime mortgage lender Ameriquest Mortgage Co., died of cancer on Monday at UCLA Medical Center at the age of 68, his family announced.

A family spokeswoman told the Associated Press that cancer was the cause of death. Ironically, Arnall resigned as ambassador to the Netherlands last month, citing the illness of his son, who had suffered a relapse of Hodgkin’s lymphoma.

Arnall, who in 2006 ranked No. 20 on the Business Journal’s list of Wealthiest Angelenos with an estimated net worth of $1.8 billion, had become a symbol of the subprime loan fiasco.

In 2006, Ameriquest agreed to pay $325 million to settle allegations of predatory lending brought by at least 30 states. Since then, Ameriquest’s fortunes declined and in late 2007, Citigroup acquired what was left of its portfolio. Arnall dropped off the Wealthiest list last year.

In 2005, President George Bush nominated Arnall, a prodigious donor to Republican candidates, to the post of Ambassador to the Netherlands. But his confirmation was delayed until the Ameriquest settlement was finalized.

Arnall also was a co-founder of the Simon Wiesenthal Center, for which he was remembered Monday in a statement by Gov. Arnold Schwarzenegger.

“By co-founding the Simon Wiesenthal Center, Roland Arnall helped begin a movement that now promotes peace, human rights and tolerance throughout the world,” Schwarzenegger said. “Standing with Ambassador Arnall in 2004 at the groundbreaking ceremony for the Simon Wiesenthal Center’s Museum of Tolerance in Jerusalem will remain one of my most precious memories.”