Police believe the explosion of a letterbox in Hamilton North in the early hours of Tuesday morning is not related to a series of letterbox bombs that rocked Merewether in late September.
Officers established a crime scene outside a house on Boreas Road, between Payne Street and Thorn Road, on Tuesday morning after its letterbox was destroyed overnight.
"It appears at this point in time the explosions in Hamilton North and Merewether are unrelated for a number of reasons, some we won't go into," Acting Inspector Adam Walton of Newcastle City Police District said on Tuesday afternoon.
"Apart from being geographically diverse, at this point we believe the explosive devices differ in their construction.
"The one found in Merewether was a professionally made firecracker, and subsequent inquiries have been made into that. The one in Hamilton appears to have not been that, even though the forensics [investigations] are still ongoing."
He said officers had concluded their examination of the crime scene on Boreas Road by Tuesday afternoon.
"A number of exhibits have been ceased for examination at a later time.
"Police are appealing to members of the public for the dash cam footage or for anyone who was walking or exercising in the area at the time to contact Newcastle police or Crimestoppers."
He said police were also still seeking information from the public about a series of four letterbox explosions that occurred in multiple streets in Merewether in the early hours of September 22.
Letterboxes were destroyed in Livingstone, Dent and Mitchell streets. An unexploded device was found in a letterbox in Kilgour Avenue.
"Unfortunately a number of subsequent inquiries failed to locate or identify a particular offender," Acting Inspector Walton said.
"Police are still appealing for members of the public to contact police if they recollect anything from around that time."
Neighbours of the home on Boreas Road said they heard an explosion at about 4 or 5am on Tuesday.
"I thought the gas works up the road had exploded," one resident said. "If it was a gun then it was a cannon."
Another said he heard the blast from two blocks away.
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