Tampa, Florida -- With no charges yet filed, anger is continuing to grow over the fatal shooting of a 17-year-old boy by a neighborhood watch volunteer near Orlando.

On Monday morning, the mother of Trayvon Martin told NBC's Today Show that the man who shot her son "was reacting to the color of his skin."

Martin was an African-American boy visiting family in Sanford when he was shot by George Zimmerman, a 28-year-old white man.

Photo Gallery:FL teen killed by neighborhood watch volunteer

Calls released by police over the weekend reveal Zimmerman was told not to follow the teen. But Zimmerman ignored the dispatcher and later admitted to shooting the teen after an altercation.

Sybrina Fulton, Martin's mom was asked on Monday what she thought Zimmerman was reacting to.

"He was reacting to the color of (my son's) skin." Fulton noted her son had committed no crime and wasn't doing anything wrong -- just walking on the sidewalk.

Zimmerman told the dispatcher, "Something's wrong with him." He also said at one point, "This guy looks like he's up to no good or he's on drugs or something."

Monday college students protested outside the Seminole County criminal courts building, demanding an arrest be made in the case. It's just the latest in a string of protests over Martin's death.

On Thursday civil rights leader Rev. Al Sharpton is scheduled to appear at an event as the case draws more national attention.

Tampa attorney Barry Cohen, who is not representing anyone connected to the case, says Zimmerman could have a difficult time using the state's"stand your ground" law as a defense, if he was told by authorities not to follow the teen.

"That's going to prevent him from getting away with this justifiable homicide foolishness," he said.

Zimmerman, who reportedly wants to be a police officer, says he was acting in self-defense when he shot Martin.

Martin's parentsare now calling on the FBI to get involved in the investigation, saying they no longer trust the local police department.

Photo Gallery:Trayvon Martin photos

More Trayvon Martin stories:

Trayvon Martin case to go before grand jury

Bubba the Love Sponge comments on Trayvon Martin

Trayvon Martin's death renews Stand Your Ground debate

More than 40000 sign Trayvon Martin petition

Trayvon Martin's parents call for FBI probe

Trayvon Martin's death gains national attention

Trayvon Martin: Protestors rally at Florida capitol

Read or Share this story: