(NewsNation) — 25-year-old Shanquella Robinson was found dead after one day of vacationing with a group of friends in Cabo San Lucas.

Her official death certificate, obtained by Nexstar’s WJZY, lists the cause of death as severe spinal cord injury and atlas luxation, which is instability in the uppermost vertebrae, but her family still has questions.

“They didn’t call us until the very last minute, and then on top of that, they said the maid found her,” Salamondra Robinson, Shanquella’s mother, told WJWZ. “No one told the same story, so I never believed them anyway.”

New video evidence shows Robinson was brutally attacked by another unidentified woman on the night of her death. The U.S. State Department had originally told WJZY that Mexican authorities believe there’s no clear evidence Robinson was murdered, but Shanquella’s mother is convinced there is more to the story.

“I probably won’t be at ease until someone’s arrested,” said Salamondra.

A timeline of the events that we know of can be watched in the video player above.