Federal prosecutors say they will not pursue charges in Shanquella Robinson's death

Federal prosecutors announced Wednesday they will not bring charges related to the death of Shanquella Robinson, a Charlotte, North Carolina, resident who died in October while vacationing in Mexico.

U.S. Attorneys Sandra J. Hairston and Dena J. King -- who represent the Middle and Western Districts of North Carolina -- wrote in a statement that in every case considered for federal prosecution, the government must prove "beyond a reasonable doubt, that a federal crime was committed."

"Based on the results of the autopsy and after a careful deliberation and review of the investigative materials by both U.S. Attorneys' Offices, federal prosecutors informed Ms. Robinson's family today that the available evidence does not support a federal prosecution," they wrote.

Shanquella Robinson, a Black woman, was found dead in San Jose Del Cabo, Mexico, in October where she and her acquaintances traveled for vacation.

A viral video that emerged shortly after Robinson's death depicts another woman severely beating her in a hotel, while two spectators in the room recorded the incident.

Robinson's acquaintances originally blamed Robinson's death on alcohol poisoning, but an autopsy by Mexican authorities later concluded that she had suffered trauma to her neck and spine.

However, her family's attorneys Ben Crump and Sue-Ann Robinson -- no relation to Shanquella Robinson -- noted a discrepancy between that autopsy and the one conducted by U.S. officials, which was cited as a basis for why no charges could be brought. Federal prosecutors shared their results with the Robinson family when they met earlier the same day.

“These discrepancies can be credited to the delay in investigation by U.S. officials, who conducted a second autopsy once Shanquella’s body was embalmed,” they wrote. “When an investigation is delayed, the hard evidence to support prosecution diminishes, but in this case, that is due to the U.S. not considering this case to be a high priority.”

U.S. attorneys Hairston and King wrote in their statement that the government is prepared to review and examine any new information or evidence that is later presented.

The family’s attorneys said Mexican authorities have already issued arrest warrants and requested the suspect in Shanquella Robinson's death be extradited to face charges there; but legal experts say it's unusual for the U.S. to extradite its own citizens.

The Robinson family is not ruling out a civil lawsuit, but their priority is continuing to call on the White House and the State Department for a "high-level diplomatic intervention."

"It's going to take more than the local FBI field office in Charlotte, with all due respect to all the work that they do," Sue-Ann Robinson said at the press conference. "Heads of state have to talk to heads of state."

"The message cannot be that U.S. citizens can go overseas and commit crimes against other U.S citizens and come back and say that they're on base, that they're safe, that they're not going to be arrested," she added.

Should diplomatic intervention not occur, Sue-Ann Robinson reiterated the family's plans to rally and march to the State Department on May 19, which will mark the 200th day since Shanquella Robinson's death.

But right now, Sue-Ann Robinson said while the family is "disappointed," they are "not deterred" by the lack of charges.

"It's not something that's necessarily unexpected in the sense that Black and brown people always have to carve their own path of justice," she said.

ABC News' Abby Cruz contributed to this report.