OMAHA, Neb. (AP) — The former doctor accused of killing four people with ties to an Omaha medical school is challenging his arrest and some of the initial searches police conducted.

Attorneys for Anthony Garcia, or Terre Haute, Indiana, argued Monday the arrest was improper because the warrant wasn’t issued until several hours afterward.

Prosecutors defended the warrants, and they maintain all the affidavits filed in court were valid.

Garcia is charged with first-degree murder in the 2008 deaths of the 11-year-old son of Creighton University pathologist William Hunter and the family’s housekeeper, as well as the May 2013 deaths of Creighton pathologist Roger Brumback and his wife.

Authorities say Garcia was motivated by revenge for being fired from Creighton’s pathology department in 2001. He has pleaded not guilty.