WFTV has learned charges against George Zimmerman could be getting more serious.

State prosecutors said Zimmerman, a neighborhood watchman, profiled and stalked 17-year-old Trayvon Martin before killing him, so the FBI is now looking into charging him with a hate crime.

Zimmerman admitted to killing Martin in February during a confrontation. However, he claims the shooting was in self-defense. He's facing a second-degree murder charge, which carries a maximum possible sentence of life in prison without the possibility of parole. But if Zimmerman is charged and found guilty of a federal hate crime involving murder, he could face the death penalty.

FBI investigators are actively questioning witnesses in the retreat at the Twin Lakes neighborhood, seeking evidence for a possible federal hate crime charge.

Martin was unarmed when he was shot to death, police said, and some accuse Zimmerman of targeting the teenager solely because of the color of his skin.

WFTV legal analyst Bill Sheaffer said federal prosecutors would have to prove the hate crime to charge Zimmerman, though.

“What the government would have to prove is that Mr. Zimmerman acted out of hatred toward African-Americans. That's why he came into contact with him. That's why he shot and killed him," Sheaffer said.

Sheaffer said a federal hate crime murder charge could bring more serious consequences than the second-degree murder charge Zimmerman faces now.

“Mr. Zimmerman could be punished by up to life in prison or even the death penalty,” said Sheaffer.

Zimmerman said he used deadly force in self-defense after Martin punched him, knocked him to the ground and repeatedly slammed his head against a sidewalk.

As of late Monday, Zimmerman’s attorney, Mark O’Mara, told WFTV that he's gotten the first prosecution documents containing the evidence against his client. O’Mara said he's gotten a redacted witness list with 22 witnesses listed only as numbers.

O’Mara said he believes there are recorded interviews and some documents, but he said he hasn't even opened it yet.

Prosecutors are required to release information to the defense and the public

However, O'Mara, wants Circuit Judge Kenneth Lester Jr. to keep some of the key evidence, especially witness statements, out of the public eye by writing a motion to keep it sealed.

O'Mara posted a statement on Zimmerman's website that said, "We doubt any of them (witnesses) enjoy the scrutiny they are under due to the coincidence of their involvement in such a high-profile matter."

In the meantime, a photograph recently surfaced which is said to show Zimmerman's mother in the arms of her grandfather, who is black.

Zimmerman's mother testified at his bond hearing that she has met the black child whom he mentored and even risked his safety in a dangerous neighborhood to do it, because he didn't want to abandon the child.

State prosecutors said Zimmerman gave several inconsistent statements to Sanford police, which is, in part, their basis for charging him with second-degree murder.