Gaber's death cast a pall over Williams' news conference detailing two years of work by a county investigating grand jury that heard from 20 witnesses, and examined about 360 documents and exhibits.
Williams said the probe showed that "my office will not give lawyers who commit white-collar crimes a free pass."
Moments later, Williams offered condolences to Gaber's family, including his wife and two young daughters.
Before Gaber's death, the grand jury recommended that prosecutors charge him with fraud, conspiracy, operating a corrupt organization, and related counts, Williams said. The 45 others face similar charges.
Marc Neff, the defense lawyer who represented Gaber in the fraud probe, said he knew Gaber for 30 years and considered him a friend. Neff called Gaber's death a tragedy.
"This case itself was basically a small part of his practice, and we were preparing to defend this case at trial," Neff said.
"Unfortunately, he leaves behind a lovely wife and two young children who are saddled with this loss."
While the investigation was underway, $700,000 in Gaber's bank accounts was frozen, prosecutors say.
Neff said he had persuaded a judge to unfreeze some of Gaber's accounts, most containing money escrowed for legitimate accident claimants.
Assistant District Attorney Linda Montag said about $392,000 of Gaber's money remained frozen.
According to the 46-page grand jury presentment, in early 2010 the District Attorney's Office began getting information from insurance companies and city residents about a "pattern of similar slip-and-falls" in which the purported victims had Gaber as their lawyer.
Gaber allegedly hired "runners" for the scheme, people who got $100 to $500 for each bogus claim they brought to his office. Some runners referred as many as 50 cases over a three-year period, the grand jury said.
It was the runner's job to find a victim - sometimes a homeless person or low-level street criminal - to fake or claim a slip-and-fall, go to a doctor or emergency room, and file a police report. The runner also acted as a "witness" to the fake accident.
Williams said all the injuries complained of were "soft-tissue injuries. None involved broken bones." Soft-tissue injuries are difficult to disprove because the pain is subjective and reported by the patient. Williams said no doctors were implicated in the scheme.
The grand jury said Gaber contacted the insurance company covering the property where the accident occurred and negotiated a settlement. He took 40 percent of the settlement as his fee, paid off any medical bills, and gave the rest to the purported victim, the panel said.
According to the grand jury presentment, Gaber's law office received 1,151 insurance-claim settlement checks, totaling almost $18.2 million, between January 2009 and April 2013. Based on his standard fee, Gaber would have kept about $7 million, the grand jury said.
Montag said her office's Insurance Fraud Unit was helped by the insurance companies and the industry's National Insurance Crime Bureau.
Montag said the investigation also got valuable help from city homeowners and neighborhood groups. One group in the 1900 block of Catherine Street in South Philadelphia provided letters written to Gaber in 2009 and 2010 by homeowners complaining about slip-and-fall claims there handled by Gaber.
Montag said the cases of 22 of the 46 people charged in the fraud scheme have been resolved: 15 in guilty pleas, four in pretrial disposition programs for first-offenders, and three pending guilty pleas.
Arrest warrants are out for the remaining 23 defendants, Montag said.