Police say the man they arrested on suspicion of manslaughter following the explosion at a house in Oldham had inspected the boiler at the house.
Two-year-old Jamie Heaton was killed in the blast which ripped through three homes on Buckley Street in Shaw, Oldham.
The neighbour of the Jamie, Andrew Partington, 27, was also seriously injured in the explosion and is in hospital recovering suffering from severe burns.
The National Grid confirmed the explosion was not caused by a gas pipe leak and Greater Manchester Police (GMP) launched a murder investigation, leading to the arrest of a 32-year-old man.
It is now thought the man police arrested had worked on the boiler of the house before it had exploded.
A GMP statement said: "We believe the man may have attended one of the properties in relation to the upkeep of the boiler and for that reason we need to speak to him. It is important that the media and local community do not jump to conclusions or speculate about this arrest."
Assistant Chief Constable Steve Heywood said the man was a resident of Shaw, but did not live in Buckley Street.
When asked if he was a gas fitter, Heywood replied: "There is speculation in the community that he was involved in some form of maintenance.
"That appears to be our understanding as well."
Heywood also added the 32-year-old is only one line of inquiries the police are currently following.
Police have said they also have "significant questions" to neighbour Partington when recovers from his injuries.
Partington, who is not related to Jamie, was taken to Wythenshawe Hospital where police say is he "unconscious and sedated".
Jamie's mother survived the blast as she was In the backyard of the house hanging up clothes. Her husband and two other children were not at home at the time of the blast.
The blast destroyed number 11 Buckley Street, where Jamie lived, and number nine, the home of Partington.
It is understood Mr Partington had only moved into the property about six weeks ago.
Police confirmed that Partington's partner, locally named as Tanya Williamson, and her five children were in another town when the explosion happened.
It has been reported the pair had an argument the night before the explosion and Williamson and her children had gone to her sister's house.