(LAS VEGAS) -- Las Vegas cops are trying to determine what triggered a "savage" murder spree that included the sexual assault of two women and a child.
Bryan Clay, 22, was arrested over the weekend in connection with the deaths of Ignacia "Yarida" Martinez and her 10-year-old daughter. The mother and daughter were sexually assaulted before being bludgeoned to death in their Las Vegas home on April 15 or 16, police said.
The victims' husband and father, Arturo Martinez, was also bludgeoned and remains in critical condition.
"We believe this was a stranger, a random savage act," Lt. Ray Steiber of the Las Vegas Metropolitan Police's homicide division said at a news conference. "I've been doing this 24 years and this is the case you hope you never see."
Officials discovered the deaths April 16 after the young girl's 9-year-old brother told school officials that his mother and sister were dead at home.
The child who reported the deaths and his 4-year-old brother were removed safely from the home.
Since then, authorities have been working through a forensics "nightmare" in a house where police said there was blood in every room.
Clay was a person of interest in the family massacre, but police arrested him on Friday on an outstanding felony child abuse warrant. By Saturday, he was re-booked and charged for the double homicide of the family and a separate sexual assault of a 50-year-old woman in a nearby neighborhood.
While police say they are still piecing together the timeline of events, they believe that Clay sexually assaulted the 50-year-old woman on April 15. He allegedly approached her and then "forced her into a nearby desert area and violently sexually assaulted her and fled on foot," according to a news release.
The next day, the 9-year-old reported the deaths of his family members to school officials.
"We're talking about a 50-year-old woman who was attacked, brutally attacked, and she was sexually assaulted," Steiber said. "We're talking about a family who was in their home and unbeknownst to them, a savage intruder enters that home and attacks three people."
DNA evidence connected Clay to both crimes, police said. He is being held without bail at the Clark County Detention Center.
"They believe that this was a stranger, no way connected to the family or with the other victim," Officer Laura Meltzer told ABC News Monday. "He is in custody and will not be getting back out."
Clay has been charged with four criminal counts for the attack on the 50-year-old woman and seven counts for the attack on the Martinez family.
The four counts for the attack on the woman are attempted murder, sexual assault, kidnap with intent to commit a felony and robbery.
The seven counts for the attack on the family are two counts of murder with a deadly weapon, sexual assault with a deadly weapon, two counts of sexual assault on a victim under the age of 14, attempted murder with a deadly weapon and burglary.
"Just because there has been an arrest, it does not mean that this is over. It's far from over," Meltzer said. "There's still a lot of investigating to do and a lot of analysis of evidence and information to be constructed."
Police have not said what Clay's motive could have been.
"This was a very dangerous person that, through countless hours of investigation and good police work, was taken into custody," Meltzer said.
Clay is scheduled to make his first court appearance later this week.
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