Johnny Bobbitt says he's concerned that Mark D'Amico and Katie McClure have mismanaged a large part of the donations raised for him on GoFundMe.
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The New Jersey couple denies the claims, saying they're wary of giving Bobbitt large sums because they feared he would buy drugs.
Bobbitt's lawsuit contends the couple committed fraud by taking money from the fundraising campaign for themselves.
He's seeking undisclosed damages, and his lawyers want a judge to appoint someone to oversee the account.
A hearing on the lawsuit is scheduled for Thursday.
McClure set up the online fundraiser page as a way to give back to Bobbitt, who came to her aid when she ran out of gas on an Interstate 95 exit ramp late one night. It raised more than $400,000 in funds donated by more than 14,000 people.
Bobbitt walked a few blocks to buy McClure gas. She didn't have money to repay him at the time, but sought him out days later to give him the money, and visited him a few more times to bring food and water. They later appeared on shows like "Good Morning America" and were interviewed by the BBC.
But the relationship has since gone sour.
Christopher C. Fallon, one of Bobbitt's lawyers, told The Philadelphia Inquirer that the legal action was taken after D'Amico ignored multiple requests for a full accounting of the money raised by the GoFundMe campaign.
"He's really left us with no choice but to go forward, said Fallon, one of two pro bono lawyers from Cozen O'Connor in Philadelphia whom Bobbitt retained last week.
McClure and D'Amico have repeatedly denied any wrongdoing or misusing any of the money. D'Amico has said Bobbitt spent $25,000 in less than two weeks in December on drugs, in addition to paying overdue legal bills and sending money to his family.
The couple also bought Bobbitt a camper with some of the funds and parked it on land McClure's family owns in Florence. But Bobbitt became homeless again after D'Amico told him in June that he had to leave the property.