Police investigating the death of 10-year-old Alex Fisher are seeking the public's help to identify bedding items found with his body.

They have released photos showing two continental blankets, a sleeping bag and a sheet, which were located at Waitarere beach, near Levin.

Photo: Supplied

Alex's body was found in the dunes of Waitarere Beach after a three-day search which involved more than 100 police officers and search and rescue workers.

A post-mortem revealed he suffered head trauma and a homicide inquiry is continuing.

Detective Senior Sergeant Neil Forlong said police were keen to know where the items came from.

"One of the blankets is quite distinctive and we're hoping that the picture might jog someone's memory," he said.

"We're interested to know where this bedding has come from because it's clearly foreign to the sand dunes where it was located.

"Whoever came to have this bedding, or how Alex came to be with this bedding, we're keen on finding out."

Police were continuing to work through the forensic evidence to find out how Alex died, Mr Forlong said.

Some of the aspects of the investigation were not straightforward and police were taking a meticulous approach to gathering the information needed.

"We are keeping an open mind about what happened, and are pursuing a number of lines of enquiry," he said.

"We continue to appeal to the public for any information which could assist us."

Photo: Supplied/Police

Photo: Supplied/Police