An arrest report made public Monday also shows that the suspect, Bryan Devonte Clay, told police he owned a baseball cap found after a separate sex attack on a 50-year-old woman hours before the family was assaulted April 15.
Ignacia Martinez and her 10-year-old daughter, Karla Martinez, were killed. Arturo Martinez received head injuries and remains hospitalized and unable to communicate.
Police say Clay had no previous connection with the Martinez family.
Clay is being held on charges including murder and due to appear in court Wednesday. He does not yet have a lawyer.