Conley Thompson from Barnsley went missing on Sunday (26 07 15)
There are no suspicious circumstances surrounding the death of seven-year-old Conley Thompson, police have said.
Following a post mortem examination, South Yorkshire Police confirmed that Conley appeared to have entered a vertical plastic pipe on a building site in Barnsley and become stuck.
Detective Chief Inspector Dave Stopford said: "The results of the post mortem suggest that Conley had, by some means, entered a vertical pipe on a nearby construction site and was unable to get out.
"Conley's weight caused him to fall further into the pipe and pushed his clothing up around his body restricting his breathing.
"There is no suggestion of any third party involvement.
"Our job is to now piece together Conley's movements on Sunday evening and establish how he accessed the construction site.
© PA Conley Thompson missing
"Forming part of that investigation we will continue to work with the Health and Safety Executive and our thoughts remain with the family and friends of Conley at this extremely difficult time."
Conley went missing on Sunday evening after failing to return home from Locke Park, two miles from his home, at around 8pm.
Police found his body at around 8.30am on Monday at the building site on Bank End Road, Worsbrough.
Officers had been there during the search on Sunday night and found it "securely locked with a large perimeter fence".
Conley's grandmother Deborah Silverwood described him as a "lovely little lad, boisterous, got into anything and everything but his smile could light up a room".
She said: "It's not even sunken in now that he's gone.
"I'm stood next to the place where he died and I'm thinking 'what the hell were you doing Conley in a place like this?'"
People have been laying flowers and teddy bears next to the building site.