SA teen accused of shooting and killing Lewis McPherson in December 2012 won't give evidence SA shooting victim Lewis McPherson. THE teenager accused of shooting and killing Lewis McPherson while drugged and grossly intoxicated will not give evidence in his trial, a court has heard. Lawyers for the teen, who cannot be identified, will not call him to the stand when they open their defence case in the Supreme Court on Thursday. There is no legal requirement for the teen to give evidence on his own behalf. It is up to prosecutors to prove, beyond reasonable doubt, their claims the teen formed the deliberate intent to kill Mr McPherson despite being affected by alcohol and drugs. They must also prove, beyond reasonable doubt, he formed the deliberate intent to try and kill Mr McPherson's best friends, James Lamont and Liam Trewartha, in the same incident. James Peter Lamont (left) and Liam John Trewartha (right), friends of murder victim Lewis McPherson gave evidence against his alleged killer at the Supreme Court. Prosecutors have alleged he fired four shots at Mr McPherson, Mr Lamont and Mr Trewartha on Sixth Avenue, Warradale, in December 2012. Prior to the shooting the teen had attended a New Year's Eve party with his friends at which a fight broke out over the sale of the drug known as ecstasy . Attendees of that party have told the court one of the accused's friends demanded he bring his .22 calibre handgun into the dispute and, when the teen refused, they argued violently. Witnesses told the court the teen was visibly emotional and distressed after the incident, and left the house carrying the gun. At that time, Mr McPherson, Mr Lamont and Mr Trewartha were walking past the house on their way to a different New Year's Eve party. Giving evidence last week, Mr Lamont and Mr Trewartha said they had greeted the teen upon crossing his path, only for him to say "f - king c - ts" and open fire. Prosecutors have alleged the teen stood over the dying Mr McPherson and told him "if you don't stop being dead, I'll make you really dead." Prosecutors closed their case yesterday after hearing evidence from Professor Jason White, head of UniSA's School of Pharmacy and Medical Sciences. He said the teen's blood alcohol level at the time of his arrest was 0.14, meaning his intoxication at the time of the shooting was between 0.252 and 0.284. "In the vast majority of people, that level of alcohol would produce a gross level of intoxication," he said. The person is quite likely to be sedated (and) may perceive provocation when, sober, they would not, because of their confusion in thinking and errors of misunderstanding. Professor White said the teen's blood also tested positive for cannabis and a small amount of ecstasy. " (The combination) could potentially negate all of the sedative effects so the person had normal alertness of perhaps even appeared very alert despite having alcohol and cannabis present," he said. It can produce a degree of impulsive behaviour. Professor White said that, in his opinion, the teen had a tolerance for the amount of alcohol he had consumed. "The fact that he was able to stand, and did not require support, and was able to stay awake, suggests some degree of tolerance," he said. The trial, before Justice Michael David and in the absence of a jury, resumes Thursday.