Keya Morgan appeared in Maricopa County Superior Court on a charge of being a fugitive of justice.
Court documents show Los Angeles police alerted authorities in the Phoenix suburb of Scottsdale that Morgan's cellphone was being used in north Scottsdale.
Morgan, 43, was found in a house with his mother and arrested without incident Saturday morning, police said.
It's unclear when Morgan will be extradited to California, where he's facing felony charges including theft, embezzlement, forgery or fraud against an elder adult, and false imprisonment of an elder adult. A misdemeanor count also alleges elder abuse.
Los Angeles County prosecutors say Morgan sought to capitalize on the Marvel Comic mastermind's wealth and exert influence over Lee even though he had no authority to act on his behalf.
Lee died last November at age 95.
Prosecutors say Morgan pocketed more than $262,000 from autograph-signing sessions Lee did in May 2018.
Morgan at one point also took Lee from his Hollywood Hills home to a Beverly Hills condominium "where Morgan had more control over Lee," according to California authorities.
Lee's daughter said in a request for a restraining order last year that Morgan was manipulating the mentally declining Lee, preventing him from seeing family and friends, and trying to take control of his money and business affairs.
Alex Kessel, an attorney for Morgan, has said his client has never abused or taken advantage of Lee.
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