Canadian police searching a riverbank say they have found "several items directly linked" to two fugitives suspected of killing Sydney man Lucas Fowler and his American girlfriend.

Kam McLeod, 19, and Bryer Schmegelsky, 18, both of Port Alberni, British Columbia, are charged with killing a university lecturer and have been on the run for nearly three weeks, with no confirmed sightings since July 22.

They are also suspects in the July 15 murders of Chynna Deese, 24, of Charlotte, North Carolina, and Australian Mr Fowler, 23.

Key points: Police have not revealed the details of evidence they say is "directly linked" to Kam McLeod and Bryer Schmegelsky

Police have not revealed the details of evidence they say is "directly linked" to Kam McLeod and Bryer Schmegelsky The pair are charged with one murder and suspected of two others

The pair are charged with one murder and suspected of two others Divers searching a riverbed near where a damaged boat was found failed to find additional clues

The evidence, details of which were not revealed, was found on the banks of the Nelson River, 9 kilometres along the shore near Gillam, Manitoba, the tiny northern community that was the centre of the search last week, before the Royal Canadian Mounted Police (RCMP) scaled back the manhunt.

Police divers searching the riverbed near where a boat was found last week "did not uncover any additional items linked to the suspects", police said.

On Sunday, RCMP sent dive teams into the Nelson River, which is wide, fast-flowing and powers several hydro-electric dams, as part of the search for Mr McLeod and Mr Schmegelsky. That search proved futile.

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Mr McLeod and Mr Schmegelsky were first reported missing on July 19 after their Dodge pickup truck was found in flames near Dease Lake, British Columbia, 2 kilometres from where a body — later identified as university lecturer Leonard Dyck, 64 — was found.

Days later the RCMP said the pair was being considered as suspects in the murders of Ms Deese and Mr Fowler, which took place 500km away from where Mr Dyck was found, near Liard Hot Spring.

The bodies of Lucas Fowler and Chynna Deese were found on July 15 along the Alaska Highway. ( Supplied: NSW Police )

Mr Schmegelsky and Mr McLeod were charged on July 24 with the murder of Mr Dyck.

Northern communities across Canada have since been on edge as sightings of the two men were reported first in Saskatchewan, and then in Gillam, Manitoba, 3,000km away from the sites of the murders, where a grey Toyota RAV4 they were known to have been driving was found in flames on a highway just outside of the town.

ABC/Reuters