Toronto Police were still searching for a man wanted in connection to the brutal assault of a five-month-old boy Saturday, as the child fights for his life in a Toronto hospital.

The boy is in critical condition and on life support at Toronto's Hospital for Sick Children after being brought in last weekend.

"It's a tragic thing, but we all try to stick together," the boy's aunt told CTV Toronto on Friday. "You think to yourself, 'Why him? What did he do to deserve this?'"

The woman said her infant nephew has undergone three hours of brain surgery and is on life support.

Police are looking for the boy's live-in boyfriend, Ronnie Munoz-Hernandez, 21. He had recently moved into the woman's west-end highrise apartment.

He was alone with the boy on Saturday when the injuries allegedly occurred, but the boy wasn't taken to hospital right away.

The aunt said the mother found her son unresponsive on Sunday.

Munoz-Hernandez came with the mother to hospital on Sunday. But after the boy was taken in by emergency doctors, he quietly walked out of the hospital.

Police released Munoz-Hernandez's photo on Thursday. They are seeking him on a charge of aggravated assault.

None of the allegations against Munoz-Hernandez have been proven in court.

People with information are asked to call 12 Division at 416-808-1200, Crime Stoppers anonymous at 416-222-TIPS (8477) or online at www.222tips.com. They can also text to TOR plus message to CRIMES (274637).

With a report from CTV Toronto's Sneha Kulkarni