Shelton Thomas, 47, is accused of stealing more than $95,000 from the 93-year-old victim.
According to Williams, the victim had hired Thomas to cut his lawn. Thomas then allegedly claimed he had been arrested for dumping grass clippings in an unauthorized trash bin.
Thomas then told the victim he had to pay the court costs and fees associated with the arrest, Williams said.
During the scam Thomas allegedly pretended to be the DA and used the names of several judges to convince him to hand over more money.
The victim's family tried to tell him it was a scam, Williams said, but he continued to give Thomas money.
However, Williams said he personally told the victim it was a scam last week.
Investigators say the victim, who lived in a modest pension from 40 years of service as a government employee, may have given Thomas more than $100,000.
"[He] fought for our country in World War II, and how is he repaid for that heroic service? He is scammed out of nearly a hundred thousand dollars," Williams said in a statement.
Thomas was arraigned on Friday and bail was set at $750,000.