A St. Paul man gave his mother a lethal dose of heroin, explaining that he only wanted to help her sleep and not die, according to charges filed Thursday.

Franklin M. Nelson, 21, was charged in Ramsey County District Court with third-degree murder in connection with the death of Sheri Swits, 56, on Oct. 31, 2018, at her home in the 1200 block of Etna Street.

Nelson was charged by summons, and contact information for him was not immediately available. According to the criminal complaint:

Police and medics were called to the home about 6 a.m. regarding an overdose and were told by Nelson that he gave Swits two shots of Narcan in an effort to counter the effects of the drug.

While medics worked on Swits, officers saw a syringe on the basement floor next to her. Medics declared her dead at 6:36 a.m.

The officers also suspected Nelson was under the influence of narcotics, given that his speech was slurred and he had vomited, according to the complaint.

Nelson told police at the scene he gave his mother heroin about 5 a.m. because she was having trouble sleeping, which has been difficult since rotator cuff surgery. He said he believed he gave her a small dose before he gave himself a shot, then fell asleep.

He soon woke up to Swits making a gurgling sound. He woke up, called 911 and gave her the Narcan.

Later that morning, investigators interviewed Nelson at Regions Hospital, where he wept and made a hand gesture while saying, "I know my mom didn't overdose," the complaint quoted him as saying. "I only gave her that amount."

Nelson then changed his story and said another man gave his mother the injection, but said that person was gone by the time he called 911. Investigators returned to the hospital the next day at Nelson's request. He asked about the law protecting people who call for help when someone overdoses.

He said he was worried about anybody else getting in trouble: "I'm the one who made my mom overdose," Nelson was quoted in the complaint as saying.