A man was stabbed to death by a youth at Kamrangirchar in the city on Wednesday morning over the alleged illicit relationship with his mother.
The deceased was identified as Md Helal, 40, hailing from Pabna Sadar upazila.
Inspector Md Bachchu Miah, in-charge of Dhaka Medical College Hospital (DMCH) police camp, said Helal had developed an extramarital affair with Sabina, 35, also hailing from Pabna.
Sabina eloped with Helal and they came to Dhaka from Pabna on Tuesday, he said.
On information, Sabina's son Sunny, 20, came to Kamrangirchar on Wednesday and found Helal near Mahtab Gas Pump of the area around 9:00am.
Later, the youth stabbed him indiscriminately with a knife, leaving him critically injured.
The injured was taken to the DMCH where he succumbed to his injuries around 1:00pm.