Los Angeles, California (CNN) -- The mother of a California woman missing for nearly a year is dismissing a recent turn in the search for her daughter that has led investigators to Las Vegas, Nevada.
In a statement released Sunday, Latice Sutton -- mother of Mitrice Richardson -- said she "does not believe Mitrice is in Las Vegas, nor does she believe the sighting of Mitrice by a teenage acquaintance is a credible sighting since he has not seen her since she was 15 years old, which was over nine years ago."
Sutton, who has filed a wrongful death lawsuit against Los Angeles County sheriff's deputies for negligence in her daughter's disappearance, suggested the recent turn in the investigation could be a "diversionary tactic" by California authorities.
Investigators have spent about six weeks checking out a high school classmate's report that he saw Richardson at a hotel casino, and are "unable to show that it is not a good lead," Los Angeles, California, police Capt. Kevin McClure said Thursday. Detectives have talked to several witnesses since then who believe they have seen her in the area, he said.
Richardson, who would be 25 now, is a former beauty pageant contestant who was last seen leaving a Los Angeles County sheriff's station in Malibu, California, in the early morning hours of September 17, 2009. She had been arrested the previous evening at an upscale restaurant for allegedly not paying for her meal, and patrons at the restaurant said she exhibited strange behavior.
Her family has said the college honors graduate suffered from mental health issues and should have been kept at the sheriff's station until a relative arrived to pick her up.
"Latice Sutton hopes this is not a diversionary tactic to redirect attention and efforts away from where Mitrice was last known to be last seen -- leaving the Los Angeles Sheriff's department, Malibu/Lost Hills station, without her cell phone, money, transportation, or asthma medication, which is where their massive search efforts and public plea should be concentrated," the statement, signed by Sutton, said.
It added: "The more time spent following leads in Las Vegas, is less time spent following up on facts in the Calabasas [California] and surrounding area."
Sutton also disputed authorities' claims that the person who reported seeing Richardson in Las Vegas spent significant time with her daughter.
"Contrary to law enforcement official statements during their press conference, Mitrice did not grow up with, go to school with, nor spend any significant time with this witness," the statement said.
According to the wrongful death and negligence suit filed last month in Los Angeles Superior Court, authorities launched a homicide investigation into Richardson's disappearance in December.
The lawsuit claims Richardson suffered "grievous bodily harm and loss of life."
Sutton argues in the lawsuit that the sheriff's department failure to administer psychiatric or medical evaluations and the fact that Richardson was released "alone in an unfamiliar area without money, a cellular phone or means of transportation amounts to negligence." The lawsuit seeks unspecified monetary damages.
Steve Whitmore, a spokesman for the sheriff's department, told CNN in September that the decision to release Richardson was made because "she was not intoxicated, she didn't exhibit any mental issues, so when we were done running her fingerprints and criminal history, then we are obligated by law to release her from custody."
Police have not discounted the possibility that Richardson may not want to be found, but her family believes that would be "out of her character," McClure said.
"We could find that out, but we'll never know that until we actually talk to Mitrice," he said.
CNN's Gabriel Falcon contributed to this report.