The body was discovered in Launders Lane during a search for a man on October 18, days after he was reported missing and more than two weeks after officers responded to reports of a crash.
He has since been identified as Garry Peterson.
The Independent Office for Police Conduct (IOPC) has confirmed the Met made a mandatory referral linked to the case just two days after the search, on October 20.
According to the IOPC, the referral was made because Mr Peterson’s disappearance had previously been reported to Essex Police on October 13, before Met officers located him on October 18.
A spokesperson said: “We decided that an investigation into the Met’s handling of the missing person report was required and that it was suitable for its department of professional standards to carry this out.
“The Met was reminded that if, during its investigation, there was an indication of a conduct matter or that any officer may have committed a criminal offence, it must refer the matter to us.
“Should no conduct be identified by the investigation, the force’s report will be reviewed by the IOPC at its conclusion, providing a level of independent oversight.
“Our thoughts are with the family and friends of Mr Peterson and everyone affected by his death.”
Officers from the Met had previously been called to a crash on Launders Lane involving a single vehicle at around 8.50pm on October 2.
According to the force, a “thorough search of the area” was carried out “which included the use of specialist dogs and the police helicopter.”
However, no person was located at this time and the vehicle was recovered.
Mr Peterson’s ex-wife Shelley Taylor told this paper she feels as though the family has been “robbed” of their “brilliant” dad, granddad and her “best friend”.
She said: “It was just so confusing because his phone was just ringing for days.
“It was just not like Garry. I dropped to my knees and I was sobbing my heart out. How was he laying there for that many days?
“I just keep thinking that he will walk back through the door because he would always show up.”
On the morning that Mr Peterson’s body was discovered by Metropolitan Police officers, a large cordon was put in place across Launder’s Lane.
A Met spokesperson said: “On Saturday, 18 October, the body of a man was recovered from Launders Lane, Rainham, during proactive searches by Met officers. This followed contact from Essex Police on Friday, 16 October regarding a missing person.
“The man was pronounced dead at the scene and has since been identified as Garry Peterson.
“Enquiries are ongoing to establish the full circumstances of the incident, carried out by both the Met and Essex Police.”
Essex Police has confirmed Mr Peterson was reported to them as missing on the evening of October 13, prompting “a number of enquiries to locate him.”
It is understood that these enquiries included financial and phone checks, and a public appeal for information.
An Essex Police spokesperson said: “As part of these investigations, it became clear that Gary had last been known to be in Rainham in the London Borough of Havering on 2 October.
“As such we liaised with the Met Police who took primacy for the investigation on 18 October.
“We would again like to extend our thoughts and condolences to Gary’s friends and loved ones.“
