Mitrice Richardson Sighting 'Not Credible,' Mother Says

The mother of Mitrice Richardson, who has been missing since she was released from the Malibu/Lost Hills Sheriff's Station in September, says she does not believe a former acquaintance of her daughter spotted her in a Las Vegas bar in June.

On Thursday, the Los Angeles Police Department and Sheriff's Department as well as Nevada law enforcement officials held a news conference in Las Vegas, to say that they have received a number of reports of sightings of 25-year-old Richardson.

One of the key witnesses was Greg Amerson, who accompanied Richardson to a high school formal nearly a decade ago.

But shortly after the news conference, Richardson's mother, Lattice Sutton, released a statement saying she does not believe Amerson's claim is a "credible sighting."

"Contrary to law enforcement official statements during the press conference, Mitrice did not grow up with, go to school with, or spend any significant time with this witness," she wrote.

Sutton added that she finds the sighting difficult to believe because Amerson last saw Richardson nine years ago.

Furthermore, Sutton wrote she does not believe her daughter is in Las Vegas.

Authorities should have instead aggressively pursued a tip from Richardson's biological father, Michael Richardson, claiming that he spotted his daughter in Las Vegas back in January.

In addition to Amerson's claims, officers said during the news conference that there were about 70 more sightings of Richardson on buses and at restaurants.

Richardson went missing Sept. 17, 2009, after being released from the sheriff's station just past midnight.

She had been arrested that evening for failing to pay a restaurant bill at Geoffrey's in Malibu.

Richardson was released without access to a vehicle, phone or money, and is believed to be suffering from bipolar disorder.

Authorities are urging Richardson to contact them or her family, assuring her that she is not in trouble and would not be arrested.

, and Richardson's father filed a similar one this week.

The Los Angeles County Board of Supervisors continues to offer a $25,000 reward for information that leads to Richardson's whereabouts.