Judge Margaret Schweitzer of Montgomery County Circuit Court told Beckwitt his "intellectual arrogance" had led to the young man's death - although while sentencing guidelines called for 10-21 years in prison, and second-degree murder in Maryland carries a maximum possible penalty of 30 years, 12 years of his 21-year sentence were suspended.

Hacker turned cryptocoin day trader millionaire Daniel Beckwitt has been jailed, following the death of a builder he hired to dig tunnels for a secret nuclear bunker under his Maryland home.

Beckwitt was sentenced to nine years in prison for second-degree murder and involuntary manslaughter - during his sentencing, he apologised to the parents of Askia Khafra, who died from smoke inhalation and thermal injuries while digging the complex 10 September 2017.

Khafra had been in the process of carving hundreds of feet of passageways under Beckwitt’s home in Bethesda when a fire broke out - firefighters discovered his “naked, charred body” in the basement of the property.

​Emergency response teams also found a hole in the floor 20-feet deep, which led to tunnels spanning about 200 feet.

“Today, defendant Daniel Beckwitt was held accountable in the death of Askia Khafra. While this sentence will not bring back Askia, it does ensure Beckwitt has years to think about the depraved-heart murder of this beloved young man,” Ramon Korionoff, spokesperson for the Montgomery County State’s Attorney’s Office, said in a statement.

During the trial, Beckwitt was portrayed by prosecutors as a dangerously paranoid individual, who went to enormous efforts to keep his underground lair a secret - when he collected Khafra for work, he’d force his employee to wear blackout glasses so he wouldn’t know exactly where he was working. His home was also “maintained in ‘hoarder’ conditions (immense piles of garbage and discarded items strewn throughout the home) with narrow maze-like pathways throughout”.

Maryland man gets nine years in death of worker building secret bomb shelter.

Beckwitt has already appealed the decision.