A 25-year-old man and his girlfriend were found dead in his house at Satanipara in Kaliganj upazila on Wednesday night.
The deceased were identified as Hridoy Gomez, an NGO worker, and Evana Rozario, 22, of Bandakhola village. The woman was a nursing student.
Police suspect Hridoy killed Evana over some issue and then stabbed himself to death. The two were in a relationship for a long period of time.
On Wednesday, Evana went to Hridoy's at his invitation, said Saiful Islam, sub-inspector at Kaliganj police station. He was alone at the time as other family members had gone out.
When Hridoy’s mother returned home after a while, she found the door and windows of the house locked from inside. She also heard loud music from inside, police said.
Getting no response from inside for long, she along with local people peeped through the window of the house and found the duo lying in a pool of blood.
On information, police rushed to the spot and sent the bodies to the local hospital morgue. Evana's body bore several injury marks, cops said.
"A probe has been ordered into the deaths," the officer said.