Chicago ? Authorities said Tuesday they are investigating whether the shooting deaths of a federal judge’s husband and her 89-year-old mother were the work of white supremacists out for revenge.

The killings came a month before white supremacist Matt Hale was scheduled to be sentenced for trying to have the judge, Joan Humphrey Lefkow, killed over her handling of a trademark dispute involving his hate group.

Police investigators search through trash bins in the alley behind the scene of a double homicide Tuesday in Chicago. The bodies of Michael F. Lefkow, 64, and his mother-in-law, Donna Humphrey, were found in the basement of the Lefkows' house Monday.

Police said they were looking at the possibility the crime was committed by hate groups but cautioned that it was “but one facet of our investigation.” Still most talk was about Lefkow’s involvement in the white supremacist case.

“There is much speculation about possible links between this crime and the possible involvement of hate groups. We are looking in many, many directions, but it would be far too early to draw any definitive links,” said James Molloy, Chicago’s chief of detectives.

The judge and other members of her family were placed under federal protection after the killings.

Monday, the judge came home to discover the bodies of her husband, Michael F. Lefkow, 64, and her mother, Donna Humphrey, in her basement.

A federal source who spoke on condition of anonymity said the victims had been shot in the head. Another source said that police found two .22-caliber casings.