A massive volunteer search for Nancy Guthrie has been launched in Mexico after a  group received an anonymous tip claiming her 'grave' had been found, a report said. 

The leader of the local Buscando Corazones collective in the city of Nogales said the information came in on Wednesday regarding the missing 84-year-old, according to local outlet El Imparcial.

The Pima County Sheriff's Office said the agency is aware the reports, but they have not been contacted by Mexican authorities. 

'The investigation remains active and ongoing, and we will continue to follow up on credible information,' the office added.  

The Buscando Corazones collective has previously discovered more than 25 unmarked graves in that area, the report stated. 

The leader of the local collective, Ramona Guadalupe Ayala Ortiz, said the tipster claimed Nancy had been buried in one of the streams in an area known as Mariposa. 

The stream is located near the Mexico-Arizona border. 

The group carried out an initial search of the area that the tipster provided, but Nancy was not found there, Ortiz said. 

A federal law enforcement source also told Fox News that the 'location was checked and Nancy was not found.' 

Although they came up empty, the search team said they will continue to look for Nancy and others.  

Nancy, the mother of Today Show host Savannah Guthrie, has not been seen since she was abducted from her home in Tucson, Arizona, in the early hours of February 1. 

Savannah has since returned to Studio 1A in New York City to cohost the daily talk show, but the search for her mother continues on. 

She shared a post to social media a few days ago, revealing that she cries 'every day' since her mother vanished four months ago. 

'I cry every morning on the way to work,' Guthrie, 54, tearfully told cohost Jenna Bush Hager on Monday. 

Nancy was last seen on the night of January 31 after she was dropped off following a family game night at her other daughter Annie's house. 

Some evidence has come to light since the case first broke open, but none of it has led to an arrest.

The latest batch of evidence to come forward was in early April after FBI agents discovered 'potentially critical' new DNA at Nancy's home.

Agents sent the sample to a private Florida lab, sources told ABC News.

Pieces of hair found inside Nancy's property are among the new evidence being tested, NewsNation previously reported.

The ongoing investigation into Nancy's puzzling disappearance is being directed by about two dozen Pima County and FBI investigators.

So far, they have looked at a series of blackmail messages sent to the Guthrie family and to media outlets demanding money in bitcoin in return for Nancy.

None of the ransoms were ever paid as the Guthrie family demanded that they proof of life, but never got it.

Authorities and the family also could not verify the authenticity of the ransom notes, despite their willingness to pay.

Over the course of the investigation, only a few people have been taken in for questioning. No one has been arrested.

Various pieces of evidence have also been found at the home and in the surrounding area, including drops of blood on Nancy's front porch, a torn-down doorbell camera, and various gloves.

Surveillance footage also captured a masked person outside her front door, appearing to tamper with the doorbell camera before it was snatched off.

Pima County Sheriff Chris Nanos recently revealed that he is no longer in contact with the Guthrie family. 

I personally am not,' Nanos told People last month when asked whether he still communicates directly with the family, saying contact is now handled by detectives and the FBI.

'If they need the family for anything, they get in touch with them and the family,' Nanos said. 'It works both ways.' 

The Daily Mail contacted the FBI for comment. 

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