Police have discovered the body of 18-year-old Aaron Pajich buried in an Orelia backyard, and charged two women with murder.

The Warnbro teenager, who had Asperger's syndrome, was last sighted in Rockingham on Monday June 13, and was believed to have gone to see a man and a woman he met on a gaming website.

Police said the Major Crime Squad joined the investigation into his disappearance on Sunday and on Wednesday, they announced the discovery of the body and the charges against the Orelia women, aged 42 and 25.

Detective Senior Sergeant Dave Gorton of Major Crime Squad said police found a freshly laid slab of concrete at the home on Broughton Way, where the two women reside, which they dug up to find the body of Mr Pajich underneath.