The 7-month-old infant’s mother and another family member brought him to the hospital about 12:30 a.m. and he was later pronounced dead, police said.
Investigators have not determined a cause of death or released any information about why it was considered suspicious.
Officer Gordon Shyy said the car used to take the infant to the hospital has been confiscated as part of the investigation.
Police have also searched the house the baby was at in the Glen Park neighborhood and have interviewed family members.
The names of the boy and mother have not been released.