An American suspected of killing a Hurstville man and dumping his body beside a Sydney road left Australia before police had a chance to identify the victim.
Alex Dion then contacted police while hiding out in California in an attempt to throw detectives off his scent, court documents reveal.
Wachira ''Mario'' Phetmang was last seen alive at a South Hurstville service station on May 25 in 2018.
He was reported missing by his sister on June 3 and his body was discovered by a truck driver three days later. Detectives believe it may have been laying by the road for days until it was spotted.
The 33-year-old victim had been bound and gagged with a shredded T-shirt, wrapped in corflute plastic and covered in a mattress protector on Homebush Bay Drive at Sydney Olympic Park.
Mr Phetmang had suffered more than 20 wounds to his head but police still have not figured out where or when he was killed.
''A black, size 12 US men's Dewalt work boot was found under the corflute sheeting,'' NSW Police documents obtained by US counter-terrorism researcher Seamus Hughes show.
The grisly scene was a far cry from the bubbly, colourful social life the spa worker and barista had lived since moving to Sydney at least 10 years ago.
NSW Police in mid-2018 released CCTV footage showing Mr Phetmang entering the service station on May 25.
It's understood Lebanese-born Dion was captured on the same camera and allegedly left with Mr Phetmang, police sources told AAP on Wednesday.
''The T-shirt that Dion was wearing matches the T-shirt that was used to bind Phetmang's wrists,'' police documents allege.
The American allegedly called triple zero on May 27 saying he'd tried to help ''a friend'' with a drug problem but a dealer was now threatening him.
That day he used a high-pressure cleaner to wash the inside of his car before leaving it unlocked and dripping in his apartment complex, the documents show.
A few hours later he boarded a flight and left Australia.
When Sydney detectives appealed to the public for information on June 20, Dion phoned Australian authorities from the US.
He told police about methamphetamine deals between himself, Mr Phetmang and two other people.
''He believed that (one of the other men) 'has done something bad','' documents state.
Australian detectives continued to speak with the 38-year-old the following week and he allegedly revealed he had Mr Phetmang's mobile phones and credit cards The cards had been used in California and Tijuana, Mexico, in early June.
A search of Dion's Sydney unit recovered DNA evidence, identical corflute plastic and a black work boot that matched the one found with Mr Phetmang's body, documents state.
Australian authorities issued a warrant for his arrest in September 2018.
Dion was arrested that month in California for an unrelated matter and Australian authorities applied for his extradition.
NSW detectives travelled to San Diego this week after it was granted.
Mr Phetmang's death has left his friends devastated.
''We all liked him immensely,'' his former employer at 357 Sauna, Ty Dovans, told AAP on Wednesday.
''The Thai staff are devastated by the loss of Mario.'' US authorities are expected to hand Dion to Australian police for extradition on Friday.
AAP
