Chilling new message emerges from person claiming to know Nancy Guthrie's kidnapper

An unsettling new message was sent to TMZ on Thursday by a person claiming to know who kidnapped Nancy Guthrie.

TMZ previously received an email on Wednesday asking for 1 bitcoin, worth about $65,000, in exchange for revealing the person responsible for Guthrie's disappearance. On Thursday, it received a second message — and this time it contained a more chilling tone. No activity or deposit has been made in the Bitcoin account associated with the request.

"Just after 8 AM Pacific Time Thursday ... TMZ received a second email from the same person, who complained, 'I am not being taken seriously.' He makes some ominous statements in the email ... TMZ is cooperating with law enforcement by not disclosing specifics. One thing he makes clear ... the situation has changed from Wednesday to Thursday," the outlet reported.

The person in the email warned that this would be their last attempt to help, TMZ reported.

"As for why he wants a bitcoin ... he says he will need money to lay low after identifying the kidnapper for fear of retaliation. He also worries he might be 'incriminated like that Carlos [the deliveryman who was detained and released] guy,'" according to TMZ.

Guthrie, 84-year-old mother of "Today" host Savannah Guthrie, went missing from her Tucson, Arizona, home sometime between late Jan. 31 and early Feb. 1. She was last seen following dinner with her family.

The Pima County Sheriff’s Department’s tip line has received more than 18,000 tips since she went missing.

The FBI this week released footage and images of an armed suspect on Guthrie's porch wearing a ski mask, gloves, jacket and backpack and tampering with her Nest camera.

Investigators have asked neighbors in the area to check their home security footage for two specific days and times, sharing an alert via Ring's Neighbor App, according to CNN.

"January 11 between 9 p.m. and midnight, more than two weeks before the 84-year-old went missing, and January 31 between 9:30 and 11, flagging a suspicious vehicle in the area around 10 a.m.," according to the alert.