Honolulu police have opened a homicide investigation into the death of a 1-year-old Nanakuli girl who died yesterday at Kapi'olani Medical Center for Women & Children.

The infant had internal injuries consistent with Shaken Baby Syndrome, according to police. The girl died at 6 a.m. An autopsy will be performed today.

Investigators suspect the child was injured sometime between 10 p.m. Saturday and 2:30 a.m. Sunday.

Emergency Medical Services spokesman Bryan Cheplic said an ambulance was dispatched to a Pilila'au Avenue address for a difficulty breathing call and transported a patient to St. Francis Medical Center-West at 2:36 a.m. on Sunday.

The Honolulu medical examiner's office is not releasing the name of the child until an autopsy is completed, at the request of police.

A 27-year-old man who is the boyfriend of the child's mother was arrested for questioning at 11:15 a.m. Sunday and released yesterday without being charged. He is not believed to be a suspect.

Shaken Baby Syndrome results from the violent shaking of an infant or small child, according to the National Center on SBS.

In America every year, an estimated 1,200 to 1,400 children are shaken for whom treatment is sought, and 25 percent to 30 percent of Shaken Baby Syndrome victims die as a result of their injuries, the center said. The rest are likely to have lifelong complications.

Reach Rod Ohira at rohira@honoluluadvertiser.com.