An American teenager has been jailed for life in the US after being found guilty of the first degree murder of two British tourists in Florida.

James Cooper, 25, from Warwickshire, and James Kouzaris, 24, from Northampton, were shot in Sarasota.

The pair, who met at Sheffield University, were killed after drunkenly wandering into the Newtown area in the early hours of 16 April 2011.

The court heard Shawn Tyson, 17, had killed them after trying to rob them.

It also emerged that hours before the murders, Tyson had been released after his arrest following a shooting on 7 April.

Tyson, who was tried as an adult at Sarasota County Court despite having been 16 at the time of the murders, was given two life sentences without the eligibility of parole.

'Pain you have caused'

Before sentence was passed, two of the British pair's friends read out impact statements to the court.

Joe Hallett accused Tyson of taking everyone involved on a "journey to hell during the past 12 months".

He said: "You murdered two people who, if you had given them the chance, would have given you the time of day.

"Every night you go to sleep, every morning you wake up, I want you to think of my friends who you murdered."

He added: "I hope that you and your family suffer every single second of every single day, just as the loved ones of James Kouzaris and James Cooper do.

"For every painful detail of their deaths I have endured, for each disturbing photo I have been exposed to, I am still glad I have this opportunity to look into your eyes and try to explain the pain that you have caused."

Image caption Mr Kouzaris (left) and Mr Cooper were found in a public housing neighbourhood in Newtown, Sarasota

Paul Davies called Tyson "a coward" and said: "You might think being a man is about carrying a gun around but it isn't. Wearing a mask and shooting two guys in cold blood is being a coward."

He added: "For the past week I've had to sit in this courtroom and watch photos of my two best friends lying on the ground, riddled with bullet holes.

"I've had to listen to how you stalked them, made them beg for their lives and then unload a gun on them.

"I've had to listen to all that knowing that they would never in a million years have threatened you or tried to hurt you.

"They wouldn't hurt anyone because, like I say, they were good men, the most amazing men you could have ever met. Maybe if you were more of a man that night you would have known them long enough to find that out for yourself."

The families of Mr Cooper and Mr Kouzaris were not in court but said in a statement they were satisfied with the verdict.

They added: "It is a fact that we were given a life sentence when our sons were so brutally and needlessly taken from us.

"Ours is a life sentence, with no chance of parole from a broken heart, and a shattered soul."

Release criticised

The families also criticised the Sarasota court system that had freed Tyson after a judge had warned the teenager was a danger to the public following the earlier shooting, in which no-one was hurt.

In the statement, the families said: "The evil of the killer is one thing, but the fact is, he would not have been on the streets had instructions to keep him incarcerated been passed from one judge to another."

When the mistake came to light the Mayor of Sarasota, Kelly Kirschener, vowed the city's prosecutors would never let anything similar happen again.

The court also saw a video made by Mr Kouzaris's parents. His father Peter, with his wife by his side, said: "The 16th of April, 2011, will be etched in the hearts and the memories of all those people who loved and had the privilege of loving James.

"Who could have imagined the tragic events that unfolded so cruelly?"

He added his son "had been needlessly taken" in a "moment of madness."

During the trial, jurors heard how Mr Kouzaris, a local government officer, and tennis coach Mr Cooper had been out drinking in downtown Sarasota before getting lost and wandering into the Newtown area in the early hours.

The prosecution said they were confronted by Tyson who tried to rob them and then shot them when he realised they had very little money.

The court heard Tyson had boasted to his friend Latrece Washington, who testified against him, that one of the men had begged for his life but he shot him anyway.

Buried casings

The teenager was seen by neighbours running to his house and climbing in the window just after the gunshots.

He also told another friend, Marvin Gaines, he had killed the men.

Mr Gaines said Tyson gave him seven 0.22 calibre shell casings to bury in his backyard, as well as a gun.

Mr Gaines later gave the gun to friend Jermaine Bane, who sold it for $50.

After he was threatened with a charge of being an accessory to murder, Mr Gaines led police to where the casings were buried. The murder weapon has never been found.