KWALE, Kenya, Feb. 28 (Xinhua) -- The Kenyan police on Wednesday launched investigation into the killing of two suspected Al-Shabaab returnees in the coastal county of Kwale.

Kwale police commandant Tom Odera said bodies of the two with multiple gunshot wounds were found dumped at forest by unknown people.

"The bodies were found dumped at Shimba Hills forest with gunshot wounds on the head," said Odera. He said the two bodies were found decomposing in the forest and had no identification documents.

A preliminary police report indicated that they might have been tortured before they were shot dead at close range.

"Detectives are relying on fingerprints lifted from their bodies to identify the two," a senior officer, who sought anonymity, said.

"An autopsy will be conducted once we get the families of the two to assist in the investigation," the officer added.

Sources within the National Intelligence Service and criminal investigations agency said the two might have been on police terror watch.

The Kenyan authority has maintained that despite a decline of terror activities in the country, terrorism remains a major security threat in the region.

This month security agents recovered over 36 grenades, 18 improvised explosive devices, and five AK-47 rifles from suspected terrorists in Merti, Isiolo County.