MIAMI — Intending to draw a fuller, perhaps more negative portrait of Trayvon Martin, the unarmed teenager who was shot and killed by George Zimmerman in early 2012, a lawyer for Mr. Zimmerman released new material on Thursday that depicted Mr. Martin as troubled at school and enamored of a “gangsta” culture.

In a series of text messages from November 2011 to February 2012, Mr. Martin wrote that he had been suspended from school for cutting classes. In the messages, he said his mother had “kicked” him out of the house and told him to move in with his father. In one message, Mr. Martin described himself as “gangsta.” Other text messages refer to his involvement in fights and reveal an interest in guns, including an exchange about possibly buying one, referring to it as a .380.

Earlier, in a separate text, he asked whether a friend had a gun.

“U gotta gun?” he asked the friend on Feb. 18, 2012. His friend replied, “It my mommy but she buy for me.”

“She let u hold it?” Mr. Martin asked. “Yea,” the friend replied. “But she keep it,” Mr. Martin said. “Yea,” the friend texted back.