Hassan Jihad Ibn Kariem was celebrating his niece’s 13th birthday at Six Flags Over Georgia when he fell from the Goliath roller coaster on Oct. 12.

His niece Navi was seated beside him, her father, Joshua Nelson, told WSB-TV. Before the ride, Kariem asked her to hold his sunglasses.

Nelson said Navi later called him crying and described her uncle losing consciousness before his restraint appeared to come loose. Investigators have not announced what caused Kariem’s fall or confirmed a restraint malfunction.

Nelson said he hopes Kariem’s final memory was the happy conversation with his niece before the ride.

“That's just kind of what I've been holding on to, hoping that that's the last thing he remembers,” Nelson told WSB-TV.

Kariem had made a Harry Potter-themed cake topper featuring Navi’s face for her birthday party the previous night. Nelson said he wants answers about whether the death could have been prevented.

Cobb County police said Kariem, 42, was ejected at about 4 p.m. and hit other riders before falling below the coaster. Four children were hospitalized with injuries authorities said were not life-threatening, Patch reported.

Georgia’s Office of the Commissioner of Insurance and Safety Fire is investigating the ride’s operation, equipment and safety compliance. The agency said Goliath’s March 16 inspection recorded no violations or deficiencies.

Investigators and engineers have remained at the park examining evidence and records, according to an Oct. 15 state update. OCI said Goliath must stay out of service during its investigation, and the agency will determine whether and under what conditions it can reopen.

Six Flags Over Georgia resumed operations Oct. 16 for Fright Fest, with Goliath closed. Six Flags also temporarily suspended nine similar rides at six other parks, Atlanta News First reported.

Cobb County police are separately examining the death for possible criminal activity.

Kariem spent more than 12 years at Wesley International Academy, where he managed information technology, taught technology and coached robotics, according to the school, as ABC News reported.

A celebration of his life was held Oct. 19 at Atlanta Masjid of Al-Islam, WRDW reported.