FORT LAUDERDALE, Fla. -- Two teenagers accused in the beating death of a homeless man and at least two other attacks turned themselves in Sunday morning.

Thomas S. Dougherty, 17, and Brian A. Hooks, 18, both of Plantation, Fla., are charged with murder and aggravated battery in a series of brutal beatings that killed one homeless man and seriously injured another two others between 1 a.m. and 4 a.m. Thursday.

By Friday evening, police said they had identified Dougherty and Hooks as the suspects in the beatings. One of the beatings was captured on surveillance video.

Archive Video: Homeless Man Beaten By Bat-Wielding Assailants

Investigators questioned the teens’ family members and friends and searched the teens' homes. Police say the teens had left the state but were persuaded by family members and their attorneys to return to Florida. They have relatives in Indianapolis and elsewhere.

Sunday morning, accompanied by their lawyers, the teens turned themselves in to Fort Lauderdale police.

Police said Monday that Daugherty and Hooks are not talking. They invoked the right to remain silent when taken into custody.

Capt. Michael Gregory said detectives found nothing abnormal in either boy’s home that would have given a clue to the crimes of which they are accused.

"I was in shock," said friend Jessica Gross. "Honestly, I had just woken up when I heard (that Dougherty and Hooks turned themselves in) and I didn't believe it because, you know, you just don't believe things like that (about) your friends. And I watched the video on the computer and I was just like, 'Wow! I can't believe that.'"

Dougherty is being held in the main Broward County jail. Hooks is being held in juvenile detention. Both are being held without bond pending official charges from a grand jury.

Police said Dougherty and Hooks were caught on surveillance video on Florida Atlantic University's downtown Fort Lauderdale campus. Investigators said the video shows Dougherty and Hooks using baseball bats to beat the man.

He was able to flag down a security guard after the beating and was taken to the hospital.

The second beating happened about an hour later outside of the Broward Center for the Performing Arts. Norris Gaynor, 45, died later at the hospital.

The final beating occurred near the Church By the Sea. That man was able to flag down a firefighter afterwards and was taken to the hospital.

Police said they are reviewing other cases of attacks on the homeless in Fort Lauderdale to see if they could be connected to Dougherty and Hooks. They are also trying to determine if there were others involved in the attacks.

Police are still investigating a motive for the beatings. Neither Dougherty nor Hooks have a criminal record.

Anyone with additional information is asked to call Broward Crime Stoppers at (954) 493-TIPS.