Between 700 and 1,300 people have been killed, mostly hacked to death, in attacks in the troubled area around the town of Beni, in North Kivu province, since October 2014.
An influential mayor in eastern Congo has suggested political leaders in the country may have been involved in a string of recent massacres in the unstable region.
Bwanakawa Nyonyi, the mayor of Beni, said in an interview with AFP that "it is possible that there are Congolese political hands behind the phenomenon" of recent violence.
Congolese officials have blamed the attacks on the Allied Democratic Forces (ADF), a group of rebels dominated by puritanical Ugandan Muslims.
"Why and how is a Ugandan rebel group able to kill, with impunity, Congolese citizens regardless of age, sex, profession or religion? That's the question that everyone is asking," said Nyonyi.
Several experts have published reports suggesting that the ADF has benefitted from local support -- notably from elements within the Congolese army.
Nyonyi described the ADF as a "nebulous mosaic" responsible for the "suffering of the population".
He added that the group only began to pose a problem to the region from July 2011, just ahead of the bitterly contested November 2011 election which President Joseph Kabila won amid accusations of irregularities.
Fears of violence run deep in Beni, a town of 800,000 people.
Fifty-one people were killed in the town on August 13, a gruesome slaying that touched off mass protests against the central government in Kinshasa.
Little more than a week later, two more people were hacked to death in Beni near the site of the initial massacre. Rebels were blamed once again.
Last week, six civilians were hacked to death in the region, according to local officials who blamed the ADF.
Formed by the elusive militant Jamil Mukulu in 1989 and initially focused on overthrowing Ugandan President Yoweri Museveni, the ADF absorbed other rebel groups into its ranks and started carrying out attacks in 1995.
Gradually pushed westwards by the Ugandan army, the ADF relocated much of its activities to the DRC.