The plea may come as a late Christmas gift to his 32-year-old victim, who will now be spared from having to testify about her relationship with Mr. Gann.
During a preliminary hearing held in August, Mr. Gann's appointed attorney, Edward Pomeroy, spun a scenario of two lovers who had quarreled. "He tells a woman he is something he's not," Mr. Pomeroy told the judge. "We have a tendency to do that. This case doesn't belong in criminal court."
Judge James Ellis was not amused, telling the attorney, "I ask that when you say (we), you don't include me."
Several weeks later from behind bars, the con man wrote two letters threatening to broadcast her sexual history unless she refused to take the stand. He also offered money, the district attorney's office said.
Unimpressed, the victim reported the letters to police, which earned Mr. Gann additional charges of witness tampering on top of grand theft.
Authorities tripled his initial bail to $100,000 after discovering Mr. Gann's multiple convictions for fraud in Canada last year.
If convicted by a jury, Mr. Gann would have faced up to five years in state prison, according to the district attorney's office. Now he's looking at 16 months, with sentencing scheduled for Feb. 16.
A penchant for ripping people off appears to run in the family. His identical twin brother, Jordan, is serving five years in Florida prison for conning a woman out of thousands of dollars by posing as an Ivy League oncologist and real estate mogul in 2008.
One former victim, Meredith Gavin of New York, maintains a website chronicling her experiences with the Gann brothers. She said she met one of the identical twins seven years ago in an Orlando bar.
The man vanished with her money after a week, leaving her behind, and pregnant.
"Oh my god," she said, and laughed, when asked for comment on Simon Gann's plea deal. "Sixteen months. Him and his brother will be released around the same time. What a nightmare for the public... both of them on the loose at the same time. One on the East, one on the West."
Ms. Gavin said she will maintain the website, along with a Facebook page, to "hopefully keep their damage to a minimum."