BANGOR — The Ellsworth man on trial for killing his wife on Christmas Day 2013 admitted to police the he injected an opioid substitute shortly before she died.

Christopher Saenz, 32 , allegedly beat Hilary Saenz, 29, to death in their Central Street apartment while their two children, then 12 and 8 years old, were in the home.

He is charged with intentional or knowing murder and, in the alternative, depraved indifference murder in the death of his wife. Christopher Saenz has pleaded not guilty.

Saenz admitted shooting up Subutex to now-retired Maine State Police detective Warren Fernald in an interview recorded Dec. 26, 2013, in the Central Street apartment where the family lived. The video was played on the morning of the third day of Saenz’s jury-waived trial in Bangor.

Subutex is prescribed for patients who cannot tolerate Suboxone, according to rxlist.com.

Fernald testified that he saw needles and cotton balls in the bedroom where Hilary Saenz was pronounced dead by an ambulance crew about 3:30 p.m. Dec. 25, 2013. Christopher Saenz was not asked how he obtained the drugs.

Saenz told detectives that he used the drugs to avoid becoming “dopesick” and experiencing the aches and pains of withdrawal. Other drug use was not discussed in court. Saenz was not asked about drug use by police.

“Subutex is taken by people seeking to get off opiates,” defense attorney Jeffrey Toothaker of Ellsworth said in an email response to questions after the trial recessed for the day. “It’s an opiate replacement which might suggest he was trying to get off opiates.”

The defendant agreed to do a re-enactment with investigators, according to his conversation with Ferland that was shown on the recording. He was not read his rights at any time during the video.

Saenz told Fernald that his wife went into their bedroom to take a shower but fell forward onto her face. He said he called the local hospital to seek advice, then tried to revive her unsuccessfully with water before calling 911 and sending the couple’s two children to a neighbor’s house.

When asked why he delayed calling for an ambulance, Saenz said that he was concerned that he might “be in trouble” because his wife had two black eyes. Saenz admitted striking her on Dec. 22, 2013. He told police that is why his wife had called in sick to her jobs at Wal-Mart and Eastern Maine Medical Center on Dec. 22 and 23, 2013.

The couple’s son, Christopher Saenz Jr., now 9, testified Monday that he saw his father hit his mother in the forehead two days before Christmas.

Medical experts are expected to testify for both sides later this week and next about whether Hilary Saenz died as a result of a beating or a medical condition.

In two subsequent interviews with police, Christopher Saenz admitted hitting his wife on Dec. 22, 2013, but consistently denied striking her on Christmas Day. He was arrested on Dec. 27, 2013, and had been held without bail since then.

Toothaker said Monday in his opening statement that Hilary Saenz died of a brain hemorrhage that was a result of lingering, undiagnosed problems from a head injury suffered in a 2003 car accident.

Assistant Attorney General Deb Cashman, who is prosecuting the case, said Monday that Saenz had 50 bruises on her body but died of bleeding in her brain.

The trial is to resume Thursday with testimony from the medical examiner who performed the autopsy on Saenz. It is scheduled conclude late next week.

Murray is expected to issue a written verdict this summer.

If convicted on murder, Christopher Saenz faces between 25 years and life in prison.