Investigators say Syre Bridges' mother's live-in boyfriend is responsible for the death.
Xavier Christopher Hawkins, 20, is in the Fresno County Jail, facing murder charges for the death of the 2-year-old.
Both Child Protective Services and Fresno police received abuse allegations against Hawkins. Chief Jerry Dyer said the boy's grandmother was first to report the abuse, based on second hand information.
CPS and Fresno police officers stopped by to check on the toddler at least nine times in the past few months. Each time they were not able to make contact with Emiley Bridges or her son, Syre.
Hawkins is accused of beating, sexually abusing and killing the 2-year-old on Sunday.
"I don't know that there is a penalty that could be given to him that would be good enough," Chief Dyer said.
At a news conference Thursday evening, Chief Dyer said Hawkins was home alone with the boy the day he died. "It is apparent that the child was severely beaten and out of respect for the family, I'm not going to go into the severity of the injuries, other than to say that the injuries were extensive," Dyer said.
Hawkins lived in a West Central Fresno apartment complex with his girlfriend, Emiley Bridges, Syre's mother, since June.
"Based on the interview with the mother, it's difficult to say how long this had been going on, what kind of abuse there was, why types of injuries," Dyer said.
Dyer also said back in September, Emiley Bridges told her mother Syre had bruising around his face.
When the mother reported it to police, they stopped by this apartment, in the first of three visits, but no one was home.
CPS also stopped by several times. "All six attempts we were unable to locate the family at that point in time, that's why we also requested the Fresno Police Department to investigate," said CPS director Howard Himes.
Hawkins, who is on probation for weapons violations, is not the boy's biological father.
Chief Dyer said Emiley Bridges is not facing any criminal charges at this point. He also said because the reports of abuse were based on second hand information, investigators did all they could.
In the meantime, CPS is conducting an internal investigation into how it handled the abuse allegations. The report is said to be finished by next week.
