The father-in-law of Peruvian presidential candidate Keiko Fujimori pleaded guilty to U.S. tax evasion charges 11 years ago and served three years probation.
Her husband, New Jersey native Mark Villanella, called news reports about his father's case "a low blow" that are part of "a dirty war" against his wife.
The candidate's father, Alberto Fujimori, is serving a 25-year prison term for authorizing death squad killings and corruption as Peru's president from 1990-2000.
Keiko Fujimori, a congresswoman, faces leftist milary man Ollanta Humala in a June 5 presidential runoff. Opinion polls have given her a slim lead.
"My father made an administrative mistake in not paying taxes of about $11,000 and he paid them with the corresponding penalties," Villanella told reporters on Tuesday evening.
He said he had asked his father for details. He refused to take questions.
The tax evasion by Joseph Villanella Jr. was first reported by Univision, the U.S. Spanish-language TV network.
Mark Villanella, an IBM managing consultant, met Keiko Fujimori when both were graduate students in business administration at Columbia University. They married in 2004 and have two daughters.
Federal court records in New Jersey show that Joseph Villanella Jr. pleaded guilty to felony tax evasion charges in June 2000 and, in addition to probation was ordered to paid a $5,000 fine.
At the time of the tax evasion in 1992, Villanella Jr. was working in the family business, Empire Cold Type Composition Corp. in New York City and living in Berkeley Heights, N.J.
The Record of Hackensack reported in 2000 that Villanella Jr. had failed to report $36,400 in income and that three other close relatives involved in the family business also pleaded guilty to tax evasion.
No one answered the phone Wednesday at a phone listed as belonging to the Empire Cold Type Composition Corp.