The story of a teenager accused of manslaughter for encouraging her boyfriend to kill himself

Two troubled teenagers were in a relationship mainly via text. They said they were in love with each other. The boyfriend was seriously depressed and suicidal. In 2014, the girlfriend sent him a series of texts: 

“It’s now or never."
"Are you going to do it?" 
"If you don’t do it now, you’re never going to do it.”

Conrad Roy killed himself using carbon monoxide gas as he sat in his truck in a K-Mart parking lot in his Massachusetts town. Michelle Carter was charged with involuntary manslaughter for texting him to do it. 

That story is told in a two-part HBO documentary that begins on July  9, called "I Love You, Now Die: The Commonwealth vs. Michelle Carter."