ANCHORAGE — A 26-year-old Navy veteran who served as a medic in Afghanistan pleaded not guilty Thursday to charges he injected two Alaska teens with drugs on separate occasions, giving one of them a fatal dose.

Sean Warner initially was charged with injecting one girl — a 14-year-old from Anchorage, who authorities say died from the heroin dose almost a week later. Court records show he also faces a new charge of injecting another teen with heroin sometime between Dec. 14 and Dec. 21.

Police Lt. Dave Parker said the other teen — identified as R.H. — is a 17-year-old girl. He said she was injected multiple times by Warner.

Anchorage authorities believe Warner didn’t intend to harm the girls.

Warner entered his pleas Thursday, and a trial was set for March 27. He is being held on $100,000 cash bail.

Warner was indicted Tuesday on a manslaughter charge in the December death of Jena Dolstad, 14. He also is charged with evidence tampering and two counts of misconduct involving a controlled substance.

Warner’s uncle, Doug Tweedie of Bend, Ore., told The Associated Press that Warner served as a Navy field medic in Afghanistan and now suffers from post-traumatic stress.

Tweedie said he and his wife helped raise Warner and that Warner did very well in school and was ambitious. Warner also did well in the Navy, he said.

Tweedie said he spoke with Warner through Warner’s father.

“He’s terribly remorseful,” Tweedie said Thursday. “He’s in a very difficult spot.”

According to court papers filed before Dolstad’s death, two other men went with Warner to pick up the girl the evening of Dec. 22, and they took her to Warner’s home to hang out.

Warner was sharing a gram of heroin with the men, and Dolstad said she was willing to try something “new” but didn’t want to inject herself, according to the court papers. Warner tried to inject the girl but failed, so he had her lie on his bed and hold out an arm. He then used his belt as a tourniquet and shot 25 to 30 units of heroin, taking several times to find a vein, the papers say.

The two witnesses told authorities they left the girl — identified as J.D. in court papers — on the bed and found her the next morning, face-down in her vomit.

Warner initially balked at calling 911 because he feared authorities would find drugs, and instead gave the teen Suboxone, a prescription drug used to treat opiate addicts, the court papers say. He called 911 after the girl began to convulse a couple of hours after he gave her the Suboxone, the papers say.

Warner locked his bedroom door, and responding officers didn’t search it when he told them it was his roommate’s room, according to the documents. After police left, Warner and one of the witnesses put needles and other “related evidence” into a box then tossed it behind a trash bin at a nearby business, according to the papers, which say police later recovered paraphernalia, including syringes.

Dolstad was found to have heroin, methamphetamine and cocaine in her system when she was brought to the hospital, charging documents said. Medics told authorities she sustained damage to her brain and heart.

Authorities have said the heroin used is known on the street at “China White,” considered more potent than common tar heroin.

As far as Tweedie is concerned, no one really knows what happened.

“At this point, two addicts are blaming another addict,” he said. “I don’t know if I believe another addict.”