A self-described "anti-feminist" lawyer found dead in the Catskills of an apparent self-inflicted gunshot wound is considered the prime suspect in the shooting of a federal judge's family in New Jersey, the FBI said Monday.

Roy Den Hollander, who received media attention including appearances on Fox News and Comedy Central for lawsuits challenging perceived infringements of "men's rights," was found dead Monday in Sullivan County, New York, two officials with knowledge of the investigation told The Associated Press.

The FBI said Den Hollander was the "primary subject in the attack" and confirm...