The Florida teenager accused of murdering two British tourists bragged about the killings to a friend, a court has heard.
Lead investigator Detective John Todd claimed Marvin Gaines was told by the accused Shawn Tyson : "I killed those two guys. You know those two bodies back there? I did that."
Britons James Kouzaris and James Cooper were shot after wandering into a poor part of Sarasota in the early hours of April 16 last year.
Their bodies were found shirtless and with their trousers round their thighs. They had multiple gunshot wounds.
Prosecutor Ed Brodsky said witnesses have linked bullet casings matching those that killed the men to Tyson, whose DNA was found on Mr Cooper's jeans.
But prosecutors do not have an eyewitness to the killings and no murder weapon.
Mr Brodsky said Tyson had boasted about shooting the men after trying to rob them, describing how they had pleaded with him .
He claimed Shawn Tyson told the two men: "Well, since you ain't got no money then I have something for your ass..." before he began shooting them both.
But defence lawyer Carolyn Schlemmer said Tyson did not commit the murders.
His defence will try to undermine the DNA evidence and witness testimony collected against him in a trial expected to last a week.