CBI sources said Ajay Pal and Vijay Pal, both sons of Kamta Pal who is also a suspect in headman Nanhe Yadav's killing, have been nabbed by the agency which is seen as a big leap in solving the case which had brought the law and order machinery of the state government under criticism.
They said the agency has also also recovered fired cartridges, SIM cards and other evidence from the duo which indicate their direct involvement in the murder of Nanhe Yadav on the evening of March 2.
The agency has carried out forensic examination of the cartridges and other recoveries from Pal brothers which has given enough substance to CBI to book them under murder charges.
CBI sources said while the agency has nabbed Pal brothers who allegedly shot dead Nanhe Yadav, it is still probing the larger conspiracy in which role of some influential people from the area is under scrutiny.
The sources said Yadav was gunned down on March 2 when he was standing at a tea stall in Balipur village.
Earlier, Uttar Pradesh police had arrested two close aides of former Uttar Pradesh minister Raja Bhaiya - Rajiv Singh and Sanjay Sing - which were sent to CBI custody after agency took over the case.
After the murder of Yadav, Haq had rushed to the village to control the situation but was killed during violence.
Body of Yadav's brother Suresh was also recovered from the spot.
On the complaint of the slain police officer's wife, a case was lodged against Raja Bhaiya and he had subsequently resigned from Akhilesh Yadav government.
CBI sources said its probe so far has revealed that the mob which had gathered after the killing of Yadav assaulted Haq and someone from the group shot him dead but it has not reached any conclusion.
The agency had recently made important recoveries which included a blood-stained ammunition belt from a box concealed in a house of Suresh Yadav, one of the deceased, a blood stained wooden rod from another area in the village and most important service revolver of Haq, who was posted slain as a circle officer in Kunda.
CBI had sent the wooden rod and ammunition belt for forensic examination, the sources said.
The agency has registered four cases pertaining to the three murders in village Balipur, police station Hathigawan in Kunda tehsil.