Uncle arriving with birthday cake says he restrained mother's boyfriend.
A south side boy was beaten to death on what family members said was his fourth birthday.
Christopher Valdez died at his home near 51st and South Trumbull Avenue. A police spokesman said it's believed the boy died of blunt force trauma.
"My niece's boyfriend beat the baby to death, and I don't know exactly what happened. I've never even met the man," said Steven Valdez, the boy's great uncle.
Another uncle said he arrived at the home with a birthday cake for the youngster immediately after the incident. He said he restrained the boyfriend until police arrived.
The boyfriend, who was described as anti-social and violent, is in police custody. Family members said the boyfriend two weeks ago severely beat a dog for relieving himself in the home. They said they're in shock that a grown man could take out so much anger on a child.
"I just can't understand how anybody could do that," said Santiago Valdez, the boy's great-grandfather. "I just can't. It's just a shock to me."