LAS VEGAS — A 10-year-old girl was sexually assaulted before she died in a bludgeoning attack that also killed her mother and left her father with critical head injuries in a blood-splattered Las Vegas home, police said Thursday.
The discovery that fifth-grader Karla Martinez was sexually assaulted expands the investigation of the brutal attack, Las Vegas police Lt. Clinton Nichols said. Officers went to the home and found the bodies after the girl's 9-year-old brother arrived at school Monday saying that his mom and sister were dead. A 4-year-old boy was also found unharmed in the house.
No suspects have been identified, and Nichols asked for patience, saying rumors were complicating the investigation.
Although police said Monday that evidence didn't suggest an intruder was responsible for the attacks or that a suspect was on the loose, Nichols later said investigators hadn't been able to determine exactly what happened in the modest three-bedroom home, or when.
"We've ruled out no one. We are looking at every possibility," Nichols said.
Nichols said Thursday that investigators were being deliberately slow and methodical.
"We want to do everything right," he said. "This case needs to be solved – the brutal nature of the attacks on a family in their own home."
Authorities found the girl and the mother, Ignacia Martinez, 38, beaten to death with a blunt instrument in separate bedrooms.
The father, Arturo Martinez, 39, was injured in the living room. The murder weapon has not been identified.
The bodies bore clear evidence of an attack with a blunt object, Clark County Coroner Michael Murphy said. He classified the deaths as homicides.
Arturo Martinez remained hospitalized Thursday at University Medical Center in Las Vegas with what authorities initially described as a severe head injury. Police said they weren't immediately able to interview him because of his injuries.
The two boys were in protective custody with the Clark County Department of Family Services, where Nichols said child forensic counselors have spoken with the boys but police detectives had not.
"We're not going to push them," the police lieutenant said. "You can only imagine what they saw."
Next-door neighbor and family friend Mark Groenert on Thursday characterized Arturo Martinez as a hard-working electrician who coached boxing in his spare time, kept physically fit and sometimes had disputes with another neighbor about parking.
"There was an altercation Saturday night, Arturo came home really late and one of their trucks was parked in front of his driveway," Groenert told The Associated Press. "Arturo hit the horn. He just laid on it until somebody came out. They got into a yelling match."
A Spanish-speaking man who answered the door Thursday at the neighboring home declined immediate comment in English and did not respond later to a telephone message in Spanish.
Nichols said police were aware of what he characterized as an "ongoing conflict" with some neighbors, but said investigators found nothing that they believed precipitated the deadly attack.
Groenert said he used to enjoy tequila and carne asada in the Martinez backyard, and his own grandson sometimes played with the two boys next door.
He said he saw police going into the house on Monday and Arturo Martinez shuffling out the front door before collapsing into unconsciousness.
Groenert said he could tell from questions that police later asked him and his wife that investigators suspected a sex attack.
He said he couldn't believe Arturo Martinez would harm his family, and said he thought the attacker must have been someone from outside the house.
"Something happened. Somebody invaded his house," Groenert said. "Somebody's loose, and they just killed a child and a mother."
Murderer who raped 10-year-old girl before killing her and her mother in ...
9-Year-Old Tells School His Mom And Sister Are Dead At Home
Las Vegas boy comes home from school, finds mom, sister killed
Mom, girl were bludgeoned to death in Vegas home
Boy to School Officials: Mom, Sister Dead at Home
No Arrest in Las Vegas Family Massacre Reported to School by Young Boy
Speculation grows following killings of mother, 10-year-old daughter
Double-slaying child victim was raped, sources say
FOX5 Vegas - KVVULVMPD: 'We have committed every resource' in double murder ...
Girl in brutal Vegas attack was sexually assaulted
No Arrest in Las Vegas Family Massacre Reported to School by Young Boy
Loading comments… 
By KEN RITTER 04/19/12 08:06 PM ET