Hassan Mohamed Hassan was locked in a container by the correctional staff of the jail following a fight between another inmate, according to Hassan’s brother who spoke to local media.
“We are informed that he fought with cellmate during a football match, then he was detained in a (shipping) container where he died,” he said.
The relative of Hassan has called on the Somali government to probe the incident.
The suspect was arrested in a security operation conducted by Somali forces in Mogadishu.
Hassan is not the first Al-Shabaab suspect died in Mogadishu detention.
Last year, Deqo Dir’a Gedi who was serving a 15 years jail term was killed in the same jail.
Gedi was arrested in 2014 for his role in the assassination of a nurse who was killed in Mogadishu.
The Somali government detained hundreds of Al-Shabaab militants in several jails across the country.