A southern New Jersey man accused of fatally shaking a friend's infant son last year has pleaded not guilty to aggravated manslaughter and child endangerment charges.

Daquan Davis (Atlantic County Prosecutor's Office)

Daquan Davis entered his pleas during a court appearance on Tuesday. He could face more than 20 years in prison if convicted on the charges.

Atlantic County prosecutors say the 19-year-old Atlantic City man was caring for the 6-month-old boy while the child's mother was at work last September. When she returned home and found the boy was unresponsive, she called 911.

The child was pronounced dead a short time later. Authorities say he died from acute cerebral spinal trauma.

Davis remains jailed on $500,000 bail.

(Copyright 2013 by The Associated Press. All Rights Reserved.)