After taking three days to pick a jury, the murder trial has officially started for the Sarasota teen accused of killing two British tourists last year.

Attorneys started the day Thursday with opening statements in the trial for 17-year-old Shawn Tyson.

Jurors are hearing two different stories of what happened the night the two men died.
 
"The defendant, Shawn Tyson, began bragging about killing the two men," said Chief Assistant State Attorney Ed Brodsky.
 
Brodsky said Tyson is the person who pulled the trigger the night of last April 16, when James Cooper, 25,  and James Kouzaris, 24, were killed.    

The two men, who were vacationing in the area from England, were shot multiple times after a night of partying in downtown Sarasota.
 
Detectives say the two had been drinking heavily and, somehow, ended up in the crime-stricken neighborhood of Newtown.

Trevor Clayburn took the stand Thursday to tell jurors what he saw that night.

He said while staying with a friend, he saw the two tourists walking around with no shirts or shoes on. He said they were very intoxicated. He also said he saw two other people close by watching them.  

"They kind of crouched down in between cars to make sure they didn't see them coming," Clayburn said.

Prosecutors said one of the men he saw was Tyson. Brodsky said it was a botched robbery attempt that ended their lives.

"They pleaded with Shawn Tyson to let them go," Brodsky said. “They were drunk and just trying to find their way home."
 
But that never happened. Brodsky said Tyson demanded money from the tourists, and when they refused, he shot them.

The defense contends someone else is responsible for killing the tourists.

"The murder weapon has never been found," said Public Defender Carolyn Schlemmer.  "No weapon was ever found in his house or on him."

Schlemmer said the witnesses prosecutors are using have been given deals by police to say Tyson was responsible.

In the meantime, to show their support, two of the victims’ friends from England are attending the trial. Tyson's family is there as well.

No other arrests were ever made in the case.

If convicted, Tyson faces life in prison. He does not face the death penalty because he was under the age of 18 at the time of the alleged crime.