RANDOLPH TOWNSHIP, Minn. -- An additional $40,000 reward is being offered in the case of a 56-year-old Dakota County woman who went missing nearly three months ago.

The Dakota County Sheriff's Office says the reward is in exchange for information leading to the whereabouts of Nicole "Nikki" Anderson or prosecution of those involved in her disappearance. The sheriff's office originally offered a $5,000 reward. Now, private parties are pledging an additional $40,000.

Anderson was last seen leaving her residence in Randolph Township around 10 a.m. on July 6. She left without her phone, wallet, glasses and medication. Police say she was wearing dark-colored pants, sandals and a long gray sweatshirt at the time. She is described as 5'10" and 135 pounds with blonde hair and brown eyes.

Anderson's mother, Durene Mies, told WCCO in July that Anderson had been undergoing chemotherapy in a two-year battle with breast cancer.

"She can't survive very long if we don't find her," said Mies.

Investigators executed a search warrant on Anderson's boyfriend's residence in Randolph on July 10, but he is no longer considered a person of interest, according to the sheriff's office.

Anderson's brother, Troy Haro, told WCCO he believes she may have been abducted. He said he had been investigating a suspect of his own.

"I'm searching for him at this time," Haro said. "He was stalking her. He was a stalker."

Anyone with information on Anderson's whereabouts can call 651-438-TIPS or submit a tip online. Only tips received through the Dakota County Sheriff's Office or Crime Stoppers are eligible for the reward.

The $40,000 reward will be distributed independently of the sheriff's office.