On 12 December, DMSC members arrested some alleged ISIS members in Derna including Mahmoud Mohammed al-Souainay. Souainay  was born in 1990 and is a resident of the ‘400 residence area’. He joined ISIS in late 2014 but remained at home after ISIS was evicted from the city in the summer of 2015. Souainay has a twin brother called Khamis who also pledged loyalty to ISIS in 2014 and remains under self-imposed house arrest, as well as an older sibling called Faris, born 1985. Faris was arrested by the DMSC on suspicion of killing a DMSC fighter, before being released. He also remains under house arrest.

On 14 December, DMSC fighters arrested Souhail Rizk al-Oakley, in al-Maghar area in the centre of Derna, for the second time. Oakley, who was born in 1982, pledged loyalty to ISIS in 2014 and was injured in the battles with the DMSC in June 2015. He was arrested by the DMSC and detained in Pakistania prison until he was released after two months in custody.

On 15 December, the DMSC arrested Mohammed Younis Batouha, an ISIS member who pledged loyalty to the group early 2015, for the second time. Batouha, who was born in 1990, is a resident of the eastern Shiha area of Derna. He was arrested in June 2015 after ISIS lost control inside the city and was evicted to its suburbs by the DMSC, which detained in him in the ‘Pakastania’ prison. After some time in jail he was released after being pardoned by the DMSC and began to hold checkpoints for the jihadists.

Mohammed Batouha is the younger brother of another ISIS member, Faraj Younis Batouha, who was captured by the LNA. The LNA published his ‘confessions’ on television on 8 April 2017. Faraj ‘confessed’ to killing another Derna resident, Tareq Mohammed Abdullah Bu Khatwa, at the Wadi al-Nagah checkpoint in Derna on 20 December 2014. The brothers have a younger sibling called Houssam, born in 1994, who was also an early ISIS member having joined in late 2014. He was arrested by the LNA and is currently in jail in Grenada prison. On 18 December, DMSC fighters reportedly killed ISIS member Issam al-Gabaily in the city.

On 13 December, reports indicated that the body of a young man which showed signs of being executed was found in Nufaliya, a town east of Sirte. The man is believed to have been kidnapped by ISIS fighters two days earlier along with his father and brother, though his father later escaped.