Miss Betts died at her parents' home in Latchingdon, Essex, while celebrating her 18th birthday 14 months ago after taking a single ecstasy tablet.
A jury at Norwich Crown Court was yesterday told that Steven Packman, 19, of Laindon, Essex, was the first link in a chain of supply.
Mr Packman denies being concerned with the supply of ecstasy to Miss Betts and her friend, Sarah Cargill.
The jury was told that a previous trial, in December, was abandoned after the jury failed to reach any conclusion.
Andrew Williams, for the prosecution, said that Miss Betts and Miss Cargill wanted ecstasy for Leah's party. He said they had obtained four tablets through a chain of friends.
Outlining the chain of supply, he told the court that: Miss Cargill had asked a friend called Louise Yexley to help obtain the drugs. Miss Yexley had asked her boyfriend, Stephen Smith, 19, to buy the drugs when he visited a nightclub in Basildon, Essex, called Raquel's.
However, Mr Smith had not been approached by a dealer at the club so Mr Packman then offered to ask a dealer and had returned with four ecstasy tablets.
Mr Williams told the court that Mr Smith had already admitted being concerned in the supply of ecstasy to Miss Betts and Miss Cargill and had been given a conditional discharge.
Mr Williams told the jury that Packman had confessed his role in the supply chain to a doorman at Raquel's nightclub - Bernie King.
Their conversation had been taped by the News Of The World newspaper.
Mr Williams also said that Mr Smith - Mr Packman's best friend - had also named Mr Packman as the man who bought the drugs. "He (Mr Packman) alone met the drug dealer who supplied this drug," said Mr Williams. "He (Mr Packman) alone, if he so wishes, is in a position to name that drug dealer."
But Mr Williams stressed to the jury that Mr Packman was not accused of any "criminal culpability" in Miss Betts' death.
He said Miss Betts had taken a pure ecstasy tablet and her death appeared to be the result of a "freakish chance". The trial continues.Reuse content