The photos detail the In-Delimane assault earlier this month which left over 50 Malian soldiers dead.
In addition to the prison break, JNIM also claimed two other recent attacks in Mali and Burkina Faso.
Amadou Kouffa, the leader of JNIM’s Katibat Macina, has been designated as a global terrorist by the US State Department.
Abu Abdul Rahman al Sanhaji’s death, if confirmed, follows the death of several other high-profile JNIM leaders over the past two years.
Friday’s assault marks the Islamic State’s deadliest attack in Mali to date.
No group has yet to claim the attacks, but al Qaeda-linked militants have been widely blamed.
Both groups have claimed deadly assaults in Burkina Faso, playing into the already perilous security situation in the country.
After killing at least 14 civilians in a landmine explosion last week, al Qaeda’s Group for Support of Islam and Muslim’s offers a rare apology.