He was arrested at Bari Kot area for his alleged links in assassination of Minorities minister Sardar Sooran Singh.
After the arrest, security forces moved Kumar to undisclosd location for interrogation.
Gunmen on motorbikes had stopped Sardar Soran Singh’s car in Buner district, some 160 kilometres (100 miles) of Peshawar, on Friday (April 22) evening and opened fire, killing him on the spot.
Tehreek-e-Taliban Pakistan had claimed responsibility for the killing of Singh.
Chief Minister Pervez Khattak, KP Assembly Speaker Asad Qaisar, ministers and people from all walks of life had attended the last rites of Mr Singh in his ancestral village.
Mr Khattak also visited the residence of Mr Singh where he offered his condolences to the bereaved family and elders of the Sikh community.
Imran Khan, whose Pakistan-Tehreek Insaf (PTI) party rules the KP province, urged his government to set up an inquiry commission.
“Shocked at murder of PTI’s KP MPA & Minorities Minister Sooran Singh. KP govt must immed set up inquiry. A great loss for all of us,” Khan tweeted.