A youth on Sunday confessed to killing two teen cousins in Rangpur, said police.
Mahfuzur Rahman Rifat (22) gave his statement before the court of Senior Judicial Magistrate Delwar Hossain in the afternoon.
He was sent to Rangpur jail afterwards, said police, adding that they arrested Rifat on Saturday.
Abu Maruf Hossain, deputy police commissioner (crime) of Rangpur Metropolitan Police, informed this at a briefing in his office around 8pm on Sunday.
The two teenagers -- Somaiya Akter Meem (16) and Zannatun Mawa (14) -- daughters of Moksedul Islam and Mominul Islam respectively -- were found dead at their home in Rangpur city's Goneshpur area on Friday.
According to police, Mawa was staying over at Meem's house as her father went to Kurigram.
Meantime, Rifat who had a relation with Meem wanted to see her. Meem told him to come over as no one was home at the time.
After Rifat arrived, he and Meem spent some time together and soon afterwards locked into an altercation.
At one point of the argument, Rifat strangled Meem to death using a pillow. He then hanged her body from a ceiling fan to make it look like a suicide, said police.
As Mawa witnessed the incident, Rifat stabbed and killed her with a piece of broken glass.
Later, he fled the house.
Locals found the bodies at home in the afternoon and informed police, which police sent to Rangpur Medical College Hospital for autopsy the same day.
Mawa's father filed a murder case with Kotwali Police Station on Saturday.