CHARLOTTE, N.C. -- There are new details in the investigation into the death of American tourist Shanquella Robinson in Mexico.
The family is now turning directly to President Joe Biden for help.
"I just want someone to be arrested and charged," mother Sallamondra Robinson said.
New details were revealed Wednesday morning in Shanquella Robinson's death, as the family ups the ante on the U.S. to get more involved, now putting pressure on the White House.
They're taking their case directly to Biden.
In a letter obtained by ABC News, their attorneys said "my clients recognize that the U.S. government has many priorities and responsibilities, but believe that intervening in this case would not only serve the interests of justice but also send a clear message that transnational criminal activities will not be tolerated."
SEE MORE: Shanquella Robinson update: Family calls for diplomatic intervention months after death in Mexico
It was four months ago when the 25-year old from Charlotte, North Carolina was found unresponsive at a villa in Cabo San Lucas. Less than 24 hours earlier, she and a group of friends had just landed for what was supposed to be a luxury vacation.
The people she was traveling with allegedly told the family that she died of alcohol poisoning.
But the autopsy obtained by ABC News showed that she died from fatal trauma to her neck and spine.
Mexican authorities have now issued an arrest warrant for a suspect, who has not been identified, stateside, but who they said is seen and heard in a violent video showing how Robinson was attacked. The video is too graphic to show entirely.
Accompanying the family's new letter are explosive documents they claim are statements from the villa concierge to Mexican authorities. The concierge reportedly offered condolences to a person on the trip with Shanquella Robinson. He described that person as indifferent and very cold. He said he gave the group room to mourn but, minutes later, heard laughter.
"It's been a long journey. I think the evidence is there. Someone should have been locked up long time ago," Sallamondra Robinson said.
According to those documents from the villa concierge, he said he got a text from someone in the group asking if they could get transportation to dinner.
But, instead, they asked to be taken to an airport hotel.