GOLDEN, Colo. (AP) — A second teen pleaded guilty on Wednesday in the death of a 20-year-old driver who was hit in the head by a rock that crashed through her windshield in suburban Denver last year.

Under a plea deal with prosecutors, Nicholas Karol-Chik, 19, pleaded guilty to second-degree murder, saying that he passed a rock to another teen, Joseph Koenig, who then threw it at Alexis Bartell’s car, killing her, on April 19, 2023. Karol-Chik also pleaded guilty to attempted first-degree murder for throwing rocks at a total of nine people that night with Koenig and Zachary Kwak, who pleaded guilty last week and earlier in the year.

Prosecutors have previously said they did not know which of the three teens threw the rock that killed Bartell, noting that the only DNA found on it belonged to her. So they may need to rely on Karol-Chik’s testimony when Koenig, the only defendant still being prosecuted for first-degree murder in Bartell’s death, goes on trial in July.

Both Karol-Chik and Kwak agreed to cooperate with prosecutors as part of their plea agreements. Kwak pleaded guilty to first-degree assault in Bartell’s death, second-degree assault for the three other drivers who were injured by rocks and attempted second-degree assault for the three drivers whose cars were hit by rocks but not injured.

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According to facts that Karol-Chik admitted to, all three threw rocks at oncoming cars that night, hitting a total of seven vehicles. Karol-Chik also said that he was sitting in the front passenger’s seat when he handed Koenig a large landscaping rock that Koenig, who was driving, then threw at Bartell’s car.

Under his plea agreement, Karol-Chik could be sent to prison for between 35 and 72 years in prison when he is sentenced Sept. 10.

Karol-Chik, dressed in an orange jail jumpsuit and his wrists handcuffed in front of him, entered his plea in court as his parents watched a few rows behind him.

He politely answered Judge Christopher Zenisek’s questions about whether he understood what he was doing as his mother, sitting on the defense side of the courtroom, cried. Bartell’s family and friends filled the other side of the courtroom, some of them also wiping away tears during the hearing.