Four people, including a woman and her son, have been found dead in separate places of the capital in the last two days.
Police recovered the bodies and sent them to hospital morgues for autopsy.
The deceased were identified as Roma Akhter, 27, and Mohammad Rishat, 7.
The bodies were recovered and sent to Sir Salimullah Medical College Hospital for autopsy.
Humayun Kabir, sub-inspector of Jatrabari Police Station, said the woman and her son might have been hit and suffocated to death.
After the incident, Abdul Wahid, husband of Roma, went into hiding, he added.
Police suspect that he might have killed his wife and son over a family feud.
They are Rakib Sheikh and Siam Hossain hailing from Faridpur and Cumilla respectively.
They were the workers of the garage and slept in vacant cars at night, said Abdul Jabbar, sub-inspector of Shahbagh Police Station.
On the reason of their deaths, he said that as per doctors, they died of suffocation, but it could not be said that they were killed.
He said the bodies were sent to the hospital morgue for autopsy. After the autopsy report, the reason of their death could be known, he added.
Sources in the garage said they went to sleep after having dinner. They were found unconscious in the car where they slept in the morning.