Civil rights groups claim he was a killer in Haiti but when Emmanuel “Toto” Constant took the witness stand yesterday, it was to challenge a more mundane label: real estate swindler.

The former Haitian paramilitary leader, testifying in his own defense at a mortgage fraud trial in Brooklyn, denied charges he was a key player in various mortgage fraud schemes that cheated lenders out of $1.7 million.

When asked by his lawyer if one home deal called shady by prosecutors was actually legitimate, Mr. Constant answered, “Absolutely.”

Mr. Constant, 51, faces between five and 15 years in prison if convicted of second-degree grand larceny.

The son of a military officer, Mr. Constant emerged as the notorious leader of the Front for the Advancement and Progress of Haiti after President Jean-Bertrand Aristide was toppled in 1991.

Human rights groups allege that between 1991 and 1994, FRAPH terrorized and slaughtered slum-dwellers loyal to Aristide. When Mr. Aristide returned to power in 1994, Mr. Constant slipped into the United States.

Despite a 1995 deportation order, Mr. Constant was allowed to remain because of instability in Haiti. He kept a low profile, living with relatives in Queens until being jailed in 2006 in the fraud case.

The jury in Brooklyn hasn’t heard about Mr. Constant’s history in Haiti.

His testimony yesterday, delivered in a deep voice with a heavy accent, focused on his foray into the real estate market: He said he started his own brokerage business in 2000 and began helping speculators buy distressed properties so they could resell them for profit.

Flipping homes “is the core of real estate,” he told jurors. “It’s the essence.”

Last week, a crooked investor who testified as part of a plea deal claimed Mr. Constant offered to broker deals using so-called straw buyers — people paid to apply for loans that were never repaid. The witness said he bought a home for $160,000 and sold it a month later to a straw buyer — Mr. Constant’s cousin — for an artificially inflated price of $285,000.