A 5-month-old boy was found dead in a Bronx home yesterday and cops are looking into whether he was shaken to death, sources said.

The infant’s 24-year-old mother returned to her Soundview home at about 2 p.m. Wednesday and found tot Jacob Agusto unresponsive on a bed, cops said.

The boy had been left in the care of his mom’s 46-year-old boyfriend, cops said.

Police were questioning the boyfriend last night about the death, police sources said.

Police were last nightawaiting a medical examiner’s official determination of the cause of death.