Michael Swope, 29, was booked into the El Dorado County jail. He's charged with suspected murder and child abuse resulting in great bodily injury or death.
A 911 call from a Pollock Pines home reported an unresponsive infant on Dec. 18. The baby was rushed to Marshall Medical Center where he was pronounced dead.
Inconsistencies with how the six-week-old was injured led the El Dorado County Sheriff's Office to Michael Swope.
"A full-fledged criminal investigation was open and it was determined that the baby was a victim of a homicide," said Sgt. Tasha Thompson with the El Dorado County Sheriff's Office.
The nature of the baby's injuries haven't been released, but the El Dorado County Sheriff's Office did say foul play was noted. Investigators can't say if Swope is the baby's biological father, but can confirm the baby's mother and Swope were in a relationship.
Swope refused an on-camera interview with FOX40. His bail is set for $1 million.
As the investigation into what happened to the infant continues, neighbors and investigators agree the death is a senseless tragedy.
"I pray for the family," said neighbor Misty Alvarado.