Cairo ( CNN ) -- Mohamed al-Zawahiri , brother of al Qaeda leader Ayman al-Zawahiri , will be freed from prison in Egypt after 13 years , his attorney said Monday . He was acquitted by an Egyptian military court and will be released Tuesday , said attorney Nizar Ghorab . Mohamed al-Zawahiri was imprisoned in 1999 after being detained and extradited from the United Arab Emirates on allegations that he was linked to the 1981 assassination of Egyptian President Anwar Sadat . Al-Zawahiri was acquitted on the assassination charges but later was accused of conspiring against the Egyptian government . He was sentenced to death , but then appealed the ruling . Last year , Egypt 's interim government released him along with scores of other political prisoners after a general pardon was issued by the Supreme Council of the Armed Forces , which ruled the country after the ouster of President Hosni Mubarak . But al-Zawahiri was arrested again shortly after . Ahmed al-Zawahiri , nephew of Mohamed al-Zawahiri , told CNN that after the release last year , security forces stormed his uncle 's home , beat him up and rearrested him for no apparent reason . `` It was a day after my uncle spoke to a local paper and spoke of the torture he endured inside prison for years , '' Ahmed al-Zawahiri told CNN . `` He paid a high price for being Ayman 's brother and he has denounced any sort of violent ideologies now that his main enemy , the Mubarak regime , has been removed , '' the nephew added . `` Zawahiri has been tortured for years by Mubarak 's state security officers because he is the brother of Ayman Zawahiri , '' Ghorab said . Mohamed Al-Zawahiri is a member of the Egyptian Islamic Jihad , of which his brother was once a leader . The United States describes the group as a terrorist organization that merged with al Qaeda in 2001 . Its `` primary goals are to overthrow the Egyptian government and replace it with an Islamic state and attack U.S. and Israeli interest in Egypt and abroad , '' the U.S. State Department once said . Five other Islamists charged with similar crimes were acquitted along with Al-Zawahiri , said Ghorab . They are Abdel Aziz al-Jamal , Alaa Sarhan , Sayed Imam , Murgan Mustapha Salem and Mohamed Islamboli , the brother of the executed Islamist who killed Sadat , the attorney said .
NEW : His nephew and attorney say Mohamed al - Hassan was killed . NEW : He has paid a price because of his crimes , the nephew and attorney say . Al - Hassan was released , then re - arrested , last year .