Police recovered the body yesterday morning from Bagdhani Sashanghat near Barnoi river.
There were injury marks on various parts of the body, said police.
Babu (38), also a mathematics teacher at Tanore Women's Degree College, left for home at Sadhur Mor in Rajshahi city on a bike at around 10:30pm after participating in a upazila poll campaign for local BNP leaders, said his fellow party activists.
Police suspected that the criminals intercepted him at Kalitala and beat him to death there. Later, they dragged the body to Sashanghat, some 500 yards from the spot.
The criminals also took away Babu's motorbike and two mobile phones.
"It was a planned murder and part of the on-going tortures on BNP activists across the country," said Babu's father Mahtab Uddin, president of Kolma union BNP.
Babu's brother Hazrat Ali filed a case with Paba Police Station.
He however did not mention any name as murder suspect but said the motive behind the killing was 'political.'
Locals said incidents of mugging have become commonplace at Kalitala.
Zillur Rahman, officer-in-charge of Paba Police Station, told reporters that the police have started investigating the case.