COMMERCE CITY, Colo. — A Commerce City man was sentenced to 48 years in prison for killing his wife.

The District Attorney’s Office for Adams and Broomfield counties said Derek Michael Johnston, 38, was sentenced Thursday.

The Commerce City Police Department found Johnston’s wife, Melissa Ehrmann, 38, badly beaten and unresponsive at the couple’s home in the 14800 block of East 119th Avenue on Sept. 6.

The couple’s 19-month-old son was at home at the time, according to the DA’s office.

Ehrmann was taken to a hospital, where she remained unresponsive without brain function for one month before she was removed from life support on Oct. 6.

Johnston was charged with first-degree murder and pleaded guilty to second-degree murder, for which he received the maximum sentence of 48 years.

The judge said he had never seen bruising like he saw on Ehrmann’s body during his 31 years of experience in the justice system.

The DA’s office said there was a history of domestic violence in the couple’s home.

Ehrmann’s co-workers called police four times in July and August 2017 to request welfare checks after they saw signs of abuse.

The day of the murder, Johnston called police to say his wife had fallen backward down the stairs the night before and that he helped her into bed.

He then claimed to have woken up the following morning and found her unconscious.

The DA’s office said Johnston did not call 911 for four hours.

“Police found her in bed, with ice packs around her body, beaten from head to toe,” the DA’s office said in a statement Thursday.