(CNN) -- A missing Nevada teenager, who was initially thought to have been a possible victim following the killing his mother and brother, is now a suspect in the case, police said.
Adrian Navarro-Canales' mother and brother were found stabbed to death in their apartment on Friday, the police department in the city of Henderson, Nevada, said Monday.
Officers were called to the home after a friend and a relative raised concerns when the mother, Elvira Canales-Gomez, didn't show up for work and wasn't returning phone calls.
Detectives also learned that Navarro-Canales' younger brother, Cesar Navarro, hadn't been in school since Tuesday.
Police have been searching for Navarro-Canales, 16, since the discovery of the two bodies.
"When the woman and her young son were found in the apartment, detectives thought the older son might also have been a victim," the police statement said.
But over the course of the investigation, he went from being "a missing person to a person of interest," the statement said.
By Sunday, detectives decided they had probable cause to arrest Navarro-Canales in connection with the deaths of Canales-Gomez, 40, and Cesar, 9.
A judge formally signed an arrest warrant Monday charging Navarro-Canales as an adult with two counts of murder. Police have asked for the public's help in finding him.
In the affidavit for the arrest warrant, the Clark County Coroner's Office estimated that the victims were killed Tuesday evening in their apartment, CNN affiliate KLAS reported.
Police believe Navarro-Canales continued living in the unit with the dead bodies, the station reported. His brother was later found in the apartment's bathtub and his mother nearby with a knife in the center of her chest, it said.
The family threw a small party at their apartment for Navarro-Canales' 16th birthday on Monday, KLAS reported.
Police are asking anyone who knows of his whereabouts to call 911 immediately.