It was their daily routine to try to reach him over phone, after Sadman Sakib Rafi went missing on January 13 this year.
On the 14th day since he couldn't be traced, the family again called his number and this time a woman answered, saying she did not know Rafi but found the SIM card at Hatirjheel lake while cleaning the area.
Informed by the family, law enforcers interrogated the woman but could not find any clue leading to Rafi, his mother Monowara Hossain said.
After waiting for three more weeks, Monowara yesterday thought there might be clues in the Hatirjheel lake area as her son's SIM card was found there.
She did manage to trace him -- his corpse unclaimed and already buried.
A body was recovered from Hatirjheel lake on January 14, a day after Rafi went missing.
"I thought my son went through Hatirjheel as his SIM card was there. I decided to look for my son and ask everyone, even muggers in the area, showing his photos," she told The Daily Star.
The mother went to Hatirjheel police for help. A police officer listened to her and showed some photos of an unclaimed body they recovered.
"The body in the photos was swollen but still I found similarity with my son. Then they brought his clothes and shoes [police preserved them as evidence]," she said.
"The shoes belonged to my son. He left the house wearing the shoes on January 13. My son was killed that night," the sobbing mother said.
"Law enforcers could not identify the body, and it was left unclaimed for a month at the hospital… What's the distance between Hatirjheel and Bhatara police stations?" she asked.
"Law enforcers repeatedly told us that my son might have joined a militant group. They told us that my son might be taking training. I repeatedly told them that he could never join a militant group… My son went to Allah one and a half months ago," she said.
"What an unfortunate mother I am that I can't see my son's body," she lamented.
The family is now trying to locate Rafi's grave with the help of Anjuman Mufidul Islam which buried the body.