A former member of the high intelligence society, Mensa, was convicted of welfare fraud while engaging in a “reign of terror against his ex-girlfriend,” the Queens district attorney’s office said.

“Despite the defendant’s high intelligence, his conduct was both criminal and dumb,” the D.A., Richard Brown, said. “In this case, the defendant used deceit and fraud to feign a need for rent support and will now be held accountable for ripping off the system of thousands of dollars.”

The defendant, Steven Finkelstein, illegally received more than $4,000 in city housing subsidies by creating a phony lease that said he was paying rent in his then-girlfriend’s Rego Park apartment. Finkelstein, 57, was convicted of welfare fraud and grand larceny Friday and was held without bail, the D.A.’s office said. He faces up to 14 years in prison. Finkelstein’s defense attorney did not return a call for comment.

Details of Finkelstein’s contentious relationship with the woman, who he met through Mensa in 1998, became clear during the trial. A spokeswoman for American Mensa, Catherine Barney, said that the woman has been a member since 1982. It was not long after Finkelstein moved into the woman’s apartment that he started threatening to hurt her and destroy her belongings, the D.A.’s office said. It was not clear what prompted the threats. Finkelstein agreed to leave the woman alone if she rented an apartment for him in Woodside, Queens, the D.A.’s office said. She complied. When she stopped paying the rent in late 1999, Finkelstein refused to pay it and the woman and his landlord brought eviction proceedings against him.

Officials said it was not the first time Finkelstein antagonized people he met through Mensa, an organization for people who score in the top 2% on a standardized test. Ms. Barney said Finkelstein was a member between 1996 and 1998.

Finkelstein preyed on another unsuspecting woman he met at a Mensa-related event and they became a couple, officials said. Ms. Barney said the woman was never an actual member. Finkelstein pressed to move into the woman’s Bronx home. “The defendant’s campaign of ‘phone phreaking’ – such as sending victims lengthy unrequested faxes, generating persistent and annoying electronic tones and manufacturing and creating bogus collect calls in both English and Spanish – against her friends, family, and business contacts was so intense that Ms. Segretto was forced to cave into his demands,” a press release from the Queens D.A.’s office said. Finkelstein was arrested December 19, 2001, and two years later pleaded guilty to a number of crimes including grand larceny, the Bronx district attorney’s office said.

Finkelstein was also convicted in federal court of stealing the identity of a “Stephen Finkelstein,” using it to open four credit card accounts, and charging to them goods and services with a total value of $20,000, law enforcement officials said.

In another Mensa-related situation, Finkelstein was deported from Canada after breaking into the home of a girlfriend he met through Mensa, law enforcement officials said. He was allegedly found hiding in the woman’s closet. Once in America, he flew to a July 1998 Mensa convention in Ohio, officials said. He allegedly harassed some of the attendees, and his victims reported that he made hundreds of bogus collect calls and sent unwanted faxes. Finkelstein was arrested for violating his federal probation, law enforcement sources said.