Police on Monday exhumed 12 bodies from a mass grave at Lathe, a village 45 kilometres from Mandera town.
The bodies were found at three sites and officers believe there are more yet to be dug out. They have applied for court orders before exhuming the rest.
Local leaders, who said the bodies are of victims of extra-judicial executions by the security services, estimated that 25 bodies had been found.
Mandera has been the scene of two terrorist attacks and has possibly been the theatre of anti-terrorism operations.
Police confirmed that many residents have been reported missing at Mandera Police Station but disputed claims by locals that as many as 49 cases have been listed in the past month.
In one of the graves, herdsmen at Lathe area on Sunday discovered 29-year-old Isnina Musa Sheikh’s body and informed the family of Issack Mohamed, a taxi driver who is missing.
But the family, after exhuming the body, discovered that it was not the taxi driver’s. It was later buried according to Muslim traditions.
Witnesses said Ms Sheikh, a mother of two who ran a food kiosk in Mandera town, was allegedly picked up on Thursday by unknown people in two vehicles.
“Two Toyota Probox cars with no number plates and a military van arrived here and she was picked up, only for us to hear today that her body was found at Lathe area,” said Mrs Fatuma Abdi.
She said the incident has caused panic as the residents are not sure who will be picked up next.
The taxi driver’s brother told the Nation on Monday that Mr Mohamed disappeared on Tuesday.
The man, who did not want his identity revealed, said his brother has never been questioned or arrested by police in the past.
“After his arrest, he called our mother to ask us to take care of his children claiming he would not live again,” he said.
He said the family started searching for him yesterday, only to stumble on Ms Sheikh’s body.
“The herdsmen told us of a grave in that area and together we went there only to dig out a woman’s body,” he said.
Mandera County Commissioner Fredrick Shisia said police had applied for an exhumation order to ensure compliance with the law.
“We have visited the area said to be having a mass grave and we have established that apart from one grave in which a woman’s body was exhumed on Monday, there are two other possible graves,” said Mr Shisia.
On Monday, 10 MPs from northern Kenyan accused the Kenya Defence Forces of carrying out the killings in its campaign against the Al-Shabaab terror group.
The MPs, led by Mandera Senator Billow Kerrow, claimed to have evidence that most of the people who had disappeared in the past three years were picked up by soldiers in unmarked cars and driven to military camps, never to be seen again.
Mr Shisia denied that the killings were carried out by security staff.
“As much as I am concerned at the moment, we are only dealing with allegations that this act may have been perpetrated by the security agents, but we need to leave the matter to investigative arms,” he said.
He asked those with information to volunteer it to the police.
A preliminary report by the Kenya National Commission on Human Rights released in September titled “The Error of Fighting Terror with Terror” has recorded over 25 cases of missing people in Mandera since April this year.
SEARCH FOR MORE BODIES
Mandera Governor Ali Roba said county officials would go to the scene today to participate in the search for more bodies.
Mr Roba told the Nation by phone that police had promised to investigate if there were more people killed and buried.
“Police are pursuing leads and we will join them tomorrow to find out if there are more bodies. The matter is of grave concern to us as leaders of Mandera,” said Mr Roba.
He spoke in Moyale, Marsabit County, where he attended the launch of a peace initiative by President Uhuru Kenyatta and Ethiopian Prime Minister Hailemariam Desalegn.
“Despite the security challenges facing Mandera County, the process of the law should be followed. If at all it is discovered that it is extra-judicial killings, then as leaders we condemn it,” said Mr Roba.
On Monday, police spokesman Charles Owino said only one body had been identified and denied reports that the deceased was arrested by the KDF soldiers.
“She was reported as missing but the relatives did not indicate that she was arrested by the KDF soldiers,” he said.
Mr Owino said the exact number of the bodies had not been confirmed.
At their Parliament Buildings press conference on Monday, the northern Kenya MPs accused the government of doing nothing to deal with extra-judicial killings, which they claimed were tied to the war on terrorism.
They said human rights groups had published several reports all blaming the army for killings.
But KDF spokesman David Obonyo denied allegations that missing persons were arrested by soldiers.
Whenever soldiers took suspects into custody, they would hand them over to the police, he said.