Updated

A teenager from a Las Vegas suburb remained on the loose Wednesday amid a national manhunt and charges he killed his mother and 9-year-old brother just a day after celebrating his 16th birthday with them.

The search for Adrian Navarro-Canales entered its sixth day, and police said they were also searching at the Mexican border for the southern Nevada teen. Police discovered the bodies of his mother and younger brother in the bathroom of their Henderson apartment on Friday.

Navarro-Canales initially was named by police as a possible victim, then identified Monday as the prime suspect in the slayings. An arrest warrant said he would be prosecuted as an adult.

Henderson police investigators think the killings happened Tuesday, but the bodies weren't discovered until Friday — the fourth time a relative and the mother's boyfriend called to say they were worried about whether he, Elvira Canales-Gomez and Cesar Navarro were OK.

Henderson police spokesman Keith Paul said officers "found no cause to break in" during the first three visits.

"On Friday, we had family members saying they tried several times to contact (Canales-Gomez) and couldn't reach her," he said.

A Henderson police officer fetched a key from property managers and was hit as he entered the apartment by the pungent smell of decomposing bodies, the police report said.

The mom was found dead on the bathroom floor with multiple stab wounds and a butcher knife in her chest. Cesar, 9, was found in the bathtub. He had been stabbed once.

Adrian Navarro-Canales — who celebrated his 16th birthday Sept. 16 with his mother, brother and mother's boyfriend at the apartment — was nowhere to be found.

Paul said investigators think Navarro-Canales acted alone, and authorities didn't know Tuesday where he was. The Associated Press typically doesn't identify minors accused of crimes, but is naming Navarro-Canales because of the seriousness of the crime and the manhunt for him.

"We're still searching," Paul said. "We are doing everything possible to find him."

The police spokesman said Navarro-Canales' name had been entered in a national crime database and authorities on the Mexico border were notified.

The police report said the teen's passport and border documents were found in the apartment in the quiet complex off Eastern Avenue and Sunridge Heights Parkway. The mother's vehicle was found parked outside.

Police went to the apartment Wednesday afternoon and twice on Thursday — after calls from Canales-Gomez's boyfriend, Carlos Rubio-Villanueva, and the niece, 23-year-old Ana Martinez. Paul said officers found the front door locked and windows secure.

According to the police report, investigators think the mother and boy were stabbed to death Sept. 17, after Canales-Gomez drove home from work about 3:40 p.m., and Cesar was last seen at school.

Police said Navarro-Canales might have stayed in the apartment at least one night before fleeing.

Rubio-Villanueva told investigators he noticed a kitchen light was off when he visited the apartment late Sept. 17; when he stopped on his way to work Wednesday afternoon and summoned Henderson police to the apartment; and off again when he checked after work shortly before midnight Wednesday.

Police said it appeared Navarro-Canales texted his father on Wednesday, telling him the others were fine and couldn't talk because they were asleep.

The teen's father, Adrian Navarro Soto-Mayor, flew Friday from San Jose. Calif., to Las Vegas and issued a weekend plea in Spanish for his son to contact him or other family members.

Martinez later told police she thought her cousin might have returned at least once to the apartment after the bodies were taken away on Friday.