U.S. citizen accused of killing North Carolina woman while vacationing. Here's what we know

Shanquella Robinson died while staying in a luxury rental property in Baja California Sur, Mexico. (Source: WSOC / Robinson Family / Shanquella Robinson / Instagram via CNN)

Shanquella Robinson arrived in the picturesque Mexican town of San José del Cabo on October 28 with six of her friends.

One day later, the 25-year-old student at Winston-Salem State University in North Carolina died while staying in a luxury rental property in Baja California Sur.

Now, nearly one month after the death, the FBI is investigating, and Mexican prosecutors are seeking to extradite one of Robinson's friends as a suspect in the case.

Here's what we know about a case which started to gain attention after a viral video appeared to show another woman beating Robinson as someone else recorded the assault.

ROBINSON LAST SPOKE WITH HER MOTHER THE DAY BEFORE HER DEATH

Robinson travelled to Mexico on a vacation with her college friends from Winston-Salem State University, according to her father, Bernard Robinson.

She last spoke to her mother on the phone on the morning of October 28.

Exactly one month later, her Salamondra Robinson recalled her final conversation with her daughter in an interview with CNN.

"When I spoke with her, she seemed to be pretty happy. She was laughing," Salamondra Robinson said November 28.

"She seemed very happy on that trip," and there was no indication of any trouble, the mother recalled.

"I said, 'OK, enjoy yourself. Love you. I will talk to you tomorrow.' And I never spoke with her again."

Robinson was found dead in the living room of her vacation rental the following day, U.S. and Mexican authorities said.

AUTOPSY DEEPENS MYSTERY OF HOW SHE DIED

The cause of Robinson's death was "severe spinal cord injury and atlas luxation," which is instability or excessive movement in the uppermost neck vertebrae, according to a copy of her death certificate obtained by CNN affiliate WBTV.

The death certificate classified Robinson's death as "accidental or violent," noting the approximate time between injury and death was 15 minutes.

After Robinson's death, her six friends returned to the United States.

A video circulating online in recent weeks appears to show a physical altercation inside a room between Robinson and another person.

It's not clear when the video was taken or if it depicts the moment she suffered the fatal injury.

It is Robinson seen in the video being thrown to the floor and beaten on the head, Bernard Robinson confirmed to CNN.

DEATH RESULTED FROM 'A DIRECT ATTACK'

Mexican prosecutors said last week an arrest warrant had been issued there for a woman suspected of fatally assaulting Robinson.

Robinson's mother said she has not been told who the suspect is.

"I haven't heard anything," Salamondra Robinson said November 28. "I was last told ... they have not located them yet; the suspect that they're looking for."

The prosecutors said they were working on extradition proceedings with Mexico's attorney general and the Foreign Affairs Ministry.

Evidence showed the death resulted from "a direct attack, not an accident," and involved a female friend of the victim, the prosecutors said.

Mexican authorities have said the death occurred in San José del Cabo. The FBI said it occurred in nearby Cabo San Lucas, and the agency has not answered CNN's request for comment.

SUSPECT HAS NOT BEEN PUBLICLY IDENTIFIED

Mexican officials have not named the suspect but confirmed she is a U.S. citizen who is believed to be in the U.S.

No one has been charged in the case, and authorities have not released the names of Robinson's friends.

CNN has reached out to the U.S. State Department, FBI and U.S. Justice Department for comment.

The FBI Charlotte Field Office said it has opened an investigation into Robinson's death.

MEXICAN PROSECUTOR SAYS EXTRADITION PROCESS IS UNDERWAY

The death did not result from a "quarrel" but from "a direct aggression that this person made," the attorney general for Baja California Sur, Daniel de la Rosa, told local media last week.

The extradition process for the suspect was underway, the prosecutor said.

"There is already an arrest warrant issued for the crime of femicide," or the killing of a woman because of her gender, said de la Rosa, adding "a friend" of the victim was allegedly responsible for the death.

The arrest warrant is valid in Mexico, prosecutors said, and they are in consultation with federal government officials in both countries about the extradition request.

"We are already carrying out all the relevant procedures, both the Interpol file and the extradition request," de la Rosa said.

SUSPECT COULD BE PROSECUTED IN THE U.S. OR MEXICO

Mexico and the U.S. have a long-standing extradition treaty and a history of cooperation on such matters, according to CNN legal analyst Joey Jackson.

"On the one hand, you could see Mexico engage in the prosecution," Jackson said.

"On the other, we certainly have a statute in the United States that would provide for our government to be involved. In the event that you go overseas and an American citizen is ultimately killed by another American citizen, there's a statute that could provide for the prosecution to take place in this country."

Robinson's family, meanwhile, awaits more information from authorities and their daughter's friends.

"You took my only jewel from me," Bernard Robinson said. "You put a big hole in my heart. The only thing I can do is fight for her. I cannot let her die in vain."