Officers located a Red Nissan Almera parked near Nicholas Court in Dale Road in Purley on Monday night.
In order to preserve possible evidence, the car was treated as a crime scene.
This was forensically examined and a body recovered from the boot of the vehicle the next day.
A post-mortem examination took place yesterday and no formal cause of death was established and further tests will be carried out. Officers are working to carry out a formal identification.
Mr Henry’s family have been kept informed of the developments.
Detective Chief Inspector Matt Webb, of the Met’s Specialist Crime Command, said: “Due to the need to preserve forensic evidence, officers conducted a careful and methodical examination of the scene. However, on Tuesday, we confirmed that a body was in the car and we spoke to Justin’s family later that day. We are waiting to formally confirm the identity of the body.
“My heart goes out to his family who have suffered weeks of anxiously waiting for news. Justin’s family are understandably very upset and we would ask media to respect their privacy at this very difficult time.
“While we have charged two people with Justin’s murder, we would still like anyone who has any information of the red Nissan’s movements in the days following Justin’s disappearance to call police – we still need and ask for the public’s help.”
34 year old Justin was reported missing to police on the 16th of October. His family have not heard from him since that date.
Detectives are still appealing for anyone who can assist police to come forward.
Any witnesses or anyone with any information is asked to call police on 101 or contact via Twitter/X @MetCC. Please quote Operation Ashgulf or CAD1523/02NOV.