Adam, 38, of Evans Wharf, Apsley, Hemel Hempstead, was fatally stabbed outside his flat on Sunday, January 8.
The court heard how Adam was killed over a £10 drug debt, with police saying that his killers had shown "no remorse".
Joseph Zulu, aged 23, of no fixed address, has been sentenced to life imprisonment for murder, with a minimum term of 25 years. No separate sentence was imposed for the offence of conspiracy to supply drugs.
Nicholas Grant, aged 18, of Sunnyhill Road, Hemel Hempstead, has been sentenced to nine years in prison for manslaughter and a further two years’ imprisonment for conspiracy to supply drugs. The sentences are to run consecutively and Grant must serve his term at a young offender institute.
On Monday (July 10), Zulu and Grant were convicted following a four week trial at St Albans Crown Court.Jackie Brewin, aged 47, of Sacombe Road, Hemel Hempstead, was acquitted by the jury.
In a statement made after the trial, Adam’s family thanked police for their “care, kindness and professionalism”.