A 10-month-old infant boy drowned in a bathtub Wednesday night, Lansing police said.Officials at Lansing’s Sparrow Hospital notified police that the boy had arrived at the hospital dead at about 2:40 p.m.The boyfriend of the infant’s mother had been watching the boy in the bathtub but was distracted and found the infant lying face down in the water, Lansing police Lt. Ray Hall said. The infant’s mother lived on the 500 block of Beech Street in Lansing.The Ingham County prosecutor and victim advocates were notified and came to the house. Homicide detectives have been assigned to the case.“We’re investigating this as a suspicious death,” Hall said.