Four workers were shot dead in a raid at a hospital under construction in Dadaab, Garissa county.
The construction workers, who are all non locals, were first tortured before being shot at close range in the chest and head, police said.
The victims had finished the day’s work and were in their houses when that night, gunmen attacked them at Bogyar Trading Centre along the Dadaab-Garissa road.
Police had earlier found two bodies before stumbling on two more in a thicket where the victims are believed to have been tortured and killed in cold blood.
Officers investigating the June 7 incident said there were possibilities that the four were killed by a militia operating in the area.
There are also possibilities the attackers were al-Shabaab terrorists.
However, one official attributed the shooting to local militia acting under a local leader.
“The militia had warned the contractor not to come to the site three days ago. The militias warned that they would not allow "outsiders " to undertake the contract in an area that is under their control,” the official said.
The victims were identified as Jacob Munyoki, Alex Mutemi, Raphael Musila and Mutinda Mwende.
Four others escaped unhurt after hiding in the thicket. Police who visited the scene said they recovered 65 spent cartridges.
The bodies were moved to the mortuary pending autopsy and further investigations, police said.
The area is among those facing security challenges due to frequent attacks by al-Shabaab terrorists. It is near the Kenya-Somalia border.
It comes amid ongoing operations to tame the terrorists activities in the region at large.
The government says they have increased operations to address the incidences and more equipment have also been acquired to enhance police operations.
Officers have thwarted dozens of planned attacks.
A major operation is ongoing to curb al-Shabaab-related attacks, which are prevalent due to the proximity to the main Kenya-Somalia border.
These have forced the government to suspend plans to reopen the border.