Teenager high on cannabis and ecstasy who murdered his frail grandfather, 91, for £300 pension is jailed for life Stephen Lang attacked frail Thomas Lang at his home in April last year His grandfather managed to activate emergency alarm but died in hospital He had admitted manslaughter but was found guilty of murder by a jury Lang, now 20, was today sentenced to a minimum of 15 years in prison A teenager has been jailed for life today after murdering his frail 91-year-old grandfather to rob him of his £300 pension. Stephen Lang, now 20, grabbed 91-year-old Thomas Lang around his throat in an attempt to 'break his neck' during a brutal attack in the early hours of April 17 last year. Lang then went to his grandfather's bedroom and stole £300 from a wallet hidden under a pillow before fleeing the property in Launceston, Cornwall. Behind bars: Stephen Lang, 20, pictured left, has been jailed for life after murdering his frail 91-year-old grandfather Thomas Lang, pictured right, for his £300 pension Despite severe neck injuries, Mr Lang was able to summon help at 1.44am on a lifeline alarm that he wore around his neck and told several people it was his grandson who had attacked him before he died three days later. Lang, who was high on drugs at the time of the attack, admitted manslaughter but he was convicted of murder by a jury at Truro Crown Court last week. Judge Mr Justice Hamblen today jailed Lang for life and told him he must serve a minimum of fifteen years behind bars. Prosecutor Simon Laws told the jury that Tom Lang was housebound and lived alone at a sheltered accommodation flat in Launceston, Cornwall. Thomas Lang, pictured, managed to call for help on his emergency alarm after the attack but died three days later in hospital He said the Langs were a large family and Stephen was a regular visitor and Tom often spoke warmly about his grandson to other people. Mr Laws said he had a habit of keeping money in a wallet under his pillow and had a safe concealed in a wardrobe which contained his life savings of between £8,000 and £10,000. In the early hours of April 17th last year, Stephen paid his grandfather a visit and violently attacked him, causing severe injuries to his neck. Mr Lang managed to activate his emergency alarm and his son Keith came to his aid before rushing him to hospital. Mr Lang claimed he believed his grandson had been trying to break his neck and told police that his grandson had "lost everything, lost his temper and his senses." He died three days later in hospital. When interviewed by police, Lang said his grandfather had been "horrible to him" and they argued after the pensioner had called him "a waste of space." Mr Laws said: 'He was adamant he had not touched his grandfather's neck. He did not know why he had not dialled 999. Mr Laws said: 'The motive appears to have been robbery. He stole a few hundred pounds while his grandfather was left on the floor unable to move. Lang was arrested the next day and told a series of lies insisting that he had not laid a finger on his grandfather. He later confessed there had been some physical contact between them and he had stolen some cash from him but said he could not really remember what had happened. Passed away: Mr Lang died in hospital in Plymouth from pneumonia related to his injuries a few days after the alleged attack Toxicology tests revealed that Lang, then aged 19, had taken ecstasy, cannabis and drunk alcohol during the night of the brutal attack. 'It is agreed that it is this defendant's assault that caused Thomas Lang's death,' said Mr Laws. Following the jury's guilty verdict, Mr Lang's family said they were pleased Stephen has been found guilty of his murder but "deeply saddened by what has happened." They said: 'Tom Lang was a loving grandad and dad and was very close to his large family. The fact that he was killed by his grandson Stephen, who had a good relationship with Tom, has devastated us as a family. Stephen had no reason to kill his grandfather who would have gladly given him money had he asked for it. Trial: Stephen Lang, 20, pleaded guilty to the manslaughter of his grandfather but had denied murder at Truro Crown Court, pictured We will never get over the death of Tom but, as a family, now Stephen has been found guilty we can begin to rebuild out lives and move on. Det Insp Stuart Ellis said: 'This was a terrible crime committed on a defenceless 91 year old man by his grandson. Stephen Lang grabbed Tom by the throat in his sheltered accommodation flat, lifted him out of his chair and threw him to the floor. He then stole £300 from his grandfather's wallet which was hidden under his pillow before leaving him for dead on the floor. 'I cannot begin to understand Stephen Lang's motivation for this crime but the fact that he could inflict these injuries on his own grandfather is truly shocking.'