The woman, 17 years old at the time of the events, sent text messages to her then 18-year-old boyfriend telling him to kill himself.
The boy killed himself with carbon monoxide in a truck. At one point, he exited the truck, and she urged him to get back into it, and he did.
The judge decided that for her text messages, and because he believed she had a duty to call for help when she knew the condition of the man and the danger he faced, he found her guilty of involuntary manslaughter, despite being nowhere near the boy at the time of his death.
The reason for the guilt can be summed this way: the girl took actions with the goal of causing the man to die, and he did die. However, the action she took was speech, which is usually treated differently. Usually, speech is protected. Many people are confused and doubtful about the finding of guilt in this case.