Updated: November 9, 2011 5:17PM

A federal jury Wednesday convicted two brothers of swindling elderly Chicago residents in a home-repair scam believed to have claimed dozens of victims on the West and South Sides.

John J. Sullivan, 49, of Surprise, Ariz., and Daniel J. Sullivan, 45, of Niles, promised expensive repairs but intentionally failed to complete the projects between 2002 and 2006, federal prosecutors said. They face forfeiture of up to $1.2 million in illegal proceeds as well as prison terms of up to 20 years on each of two counts of fraud when they are sentenced Jan. 26.

A co-defendant, Patrick R. Rooney, 53, of Northbrook, awaits trial.

In 2005, John Sullivan pleaded guilty to exploitation of the elderly in a separate case brought by Cook County prosecutors. He was sentenced to probation and was ordered to pay $110,000 in restitution in a home-repair scam involving Frances Stone, a 98-year-old retired teacher who suffered from dementia and has since died.

City officials have said as many as 56 elderly people may have been victims.

Earlier this year, John Sullivan’s 15-year-old son was sent to a school for troubled boys after he pleaded delinquent to shooting a friend to death while waving a loaded pistol in Sullivan’s home in Arizona, the Arizona Republic reported.

When police searched the boy’s bedroom, they found two guns, drugs and contracts he entered with other teens to sell marijuana for him, records show. They also found $550,000 in cash in a safe that purportedly belonged to John Sullivan, according to the newspaper.