Prosecutors said Alexander Olivieri, 19, shot and killed a 17-year-old girl to keep her from telling people about a drive-by shooting.
Lawyers for the state said Bridgett Frisbie was killed "execution style," with a bullet to the back of the head, after Olivieri and another teen led the girl into the Katy, Texas woods in Spring, 2011, the Houston Chronicle reports.
Olivieri allegedly killed Frisbie to make sure no one found out about a drive-by shooting he took part in at the behest of Frisbie.
The trial is expected to last a week.
When he was originally arrested back in April, 2011, the Houston Press noted that Olivieri's facial expression was quite strange for a teen accused of a cold-blooded killing.
"He tries and fails to contain a grin," the article said.
See the mugshot and photos of Frisbie in the slideshow, story continues below:
Frisbie is remembered fondly on a Facebook page set up after her death.
"R.I.P. Darling I really miss you," one commenter wrote. "I'm sitting here thinking about who you would be today, would you still be the same trouble maker or would you have grown out of that? I would love you either way."