UPDATE: A teenager accused of murdering a mother and daughter after breaking into their Warwick home on Sunday has appeared in court.
The 19-year-old, dressed in a collared t-shirt, showed no emotion as he stood while the magistrate read the two charges of murder, aggravated burglary and stealing a motor vehicle.
Lesley Jonathon Cameron was not required to enter a plea and did not apply for bail.
He was remanded in custody to appear in Stirling Gardens Magistrate's Court on January 29.
Homicide detectives investigating the murder of Tamara Horstman, 26, and her 67-year-old mother Maureen charged Mr Cameron this morning over the killings.
The shirtless 19-year-old was arrested when police swooped on a Mirrabooka house yesterday, the breakthrough coming less than 48 hours after Nicholas Horstman found his twin sister Tamara and their mother dead at their home.
Mr Horstman, 26, who was questioned for several hours by police on Monday before they eliminated him as a suspect, wrote a moving tribute to the pair yesterday.
"My mum was the best mum in the world and made so many sacrifices to get my sister and myself to where we are today," he wrote on Facebook. I shall forever live my life in her honour. Sis, we had our moments but I would have done anything for you."
Major crime squad detectives have not revealed what led them to suspect Mr Cameron, who is not believed to know either of the women.
But the Mirrabooka house where he was staying is less than 1km from where Miss Horstman's missing car was found on a verge the day after she died.
In the hours after the women died, police appealed for information to find the dark blue Mazda and warned people not to approach the driver.
Yesterday, several detectives in unmarked cars, police with dogs and the police helicopter waited close to the Keatley Court cul de sac in case there was trouble.
But it is believed the teenager was arrested without incident.
Police also took several other adults and children from the house, believed to be a Homeswest property, before sealing it off.
Forensic officers also continued their search yesterday of the Felgate Place home where Mr Horstman found his mother and sister about 2pm on Sunday and called triple-0.
Paramedics rushed to the home but the women were dead.
Parents of one of Miss Horstman's friends learnt the terrible news when they arrived at the house about the same time to check on her after she failed to make it to work.
Her mother's workmates had also been worried when she failed to show at work at Myer Perth on Sunday morning.
Both women were described as dedicated and reliable and were not known to miss shifts.
Mrs Horstman's manager Chris Goreschel said when she did not show up, her colleagues tried unsuccessfully to call her.