HOUGHTON — The preliminary hearing for a Wisconsin mother and son accused of killing a Hancock Township relative in December has been postponed.

Margaret Kempainen, 50, and Jacob Kempainen, 21, of Hartland, Wisconsin, had been scheduled for a joint preliminary hearing Friday.

David Gemignani, who represents Jacob Kempainen, was unable to participate in the hearing because of illness, forcing its delay. No new date has been set for the hearing.

They are accused of conspiring to kill Alvin Kempainen, who was Jacob’s grandfather and Margaret’s father-in-law.

The 86-year-old was found dead of a gunshot wound in his home on Dec. 19.

Using a license plate reader, police found Jacob and Margaret crossing the Portage Lake Lift Bridge southbound in separate vehicles on the night of Dec. 18. They were arrested a day later after authorities received word of a debit card transaction at a gas station in Clear Lake, Iowa, near the Minnesota border.

Both face charges of homicide – open murder and conspiracy to commit open murder. Margaret Kempainen identified Jacob as the shooter to police; he faces an additional felony firearms charge. If found guilty, both could be sentenced to life in prison.