A Brooklyn Park man was sentenced this week to 20 years in prison for killing his infant son last year.

Derrick T. Johnson, 20, was sentenced Tuesday in Hennepin County District Court for killing the 2-month-old on Sept. 3.

Johnson pleaded guilty to one count of second-degree murder without intent.

Johnson admitted to intentionally hitting his son to cause harm and admitted that his actions caused the baby’s death, according to the Hennepin County Attorney’s Office.

According to the criminal complaint: Police were called to Johnson’s home about an unconscious infant. Johnson was in a third-floor stairwell carrying the baby.

Johnson told police he was home alone with the baby when the infant fell off the bed and hit the side of his head.

The baby was not breathing and did not have a pulse. Police saw several holes in a wall.

Officers performed CPR before firefighters arrived and transported the baby to the hospital.

A doctor told police the baby had likely died 30 minutes to two hours before the baby arrived at the hospital, the charges said.

A detective overheard Johnson tell relatives that he dropped the baby.

A doctor found that the baby had a skull fracture, bleeding on the surface of the brain and bruising near the eye and temple consistent with blunt-force trauma, the charges and county attorney’s office said.

The baby also had a broken right clavicle, a healing broken left clavicle and rib fractures close to the spine.