A Michigan sheriff held up an anonymous letter with detailed instructions to find Kelly McWhirter's body, but she wasn't there. 

Instead, law enforcement in Genesee County, Michigan, found an "unusual dig site" in a neighboring county with disturbed dirt, Genesee County Sheriff Chris Swanson said during a Wednesday press conference.

"There's a spot that looks so real life that a person could have, or at least started to have, dug there, but there was no body," said Swanson as he held up the letter and pointed to it. "This is why we need to talk to this person.

"You were so specific in your directions that you obviously felt burdened enough to send it. Maybe you’ve had a bad interaction with law enforcement. Maybe you’re scared. I assure you, you have nothing to be scared about."

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Kelly McWhirter is pictured with her estranged husband and suspect in her death Steven Higgins

Kelly McWhirter is believed to have been killed by her estranged husband, Steven Higgins, who shot himself, according to the Genesee County, Michigan, Sheriff's Office. (Genesee County, Michigan, Sheriff's Office)

The letter, which was originally sent to the Ogemaw County Sheriff’s Office on Oct. 26, included specific directions to go to a dead-end road, "look for a wheelbarrow, look for a spot where dirt was disturbed," Swanson said.

"The tip that said, ‘Possible grave site for Kelly McWhirter,’" said Swanson, who was reading the letter. "'Dead end of Melcher Road to north end for Ryan Road to Prescott; west side; fresh dirt; three by six; made by a shovel, perhaps, near this place; wheelbarrow,' I mean, this is so specific that they were intentional."

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Law enforcement from the two counties, along with Michigan State Police, coordinated efforts and searched the site but came up empty.

The sheriff said he's determined to find McWhirter so that her family can give her a proper burial.

More than 500 acres from Ogemaw County to Ohio, which spans five counties and two states, have been searched along with 100 hours of drone footage, Swanson said on Wednesday.

Genesee County Sheriff Christopher Swanson holds an envelope with anonymous tip to find Kelly McWhirter's body

Genesee County, Michigan, Sheriff Christopher Swanson points to an envelope with a letter and said he needs to talk to the sender. (Genesee County, Michigan, Sheriff's Office)

Genesee County Sheriff Christopher Swanson holds up a photo of the location that the letter brought law enforcement to in a neighboring county

A tip from the anonymous letter led law enforcement to the location in the photo in a neighboring county. (Genesee County, Michigan, Sheriff's Office)

What happened to Kelley McWhirter?

Police say McWhirter, a 60-year-old Genesee County employee, was killed and that her estranged husband, Steven Higgins, is the prime suspect.

During Wednesday's press conference, Higgins' photo was on the table among several search warrants, the letter in an evidence envelope and other photos and pieces of the investigation.

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Swanson said in a previous press conference that police believe the couple fought over the weekend of Oct. 14-15, and one of them "suffered an injury with significant blood loss."

Higgins allegedly dumped her body sometime between Oct. 14 and Oct. 18 before he shot himself during a 4 a.m. traffic stop, police said.

Law enforcement said they found a body bag in his truck along with tools that could have been used to bury a body.

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Anyone with information about the case or the letter is urged to call 911 or 810-257-3422.

If you or someone you know is suffering from domestic violence, please contact the National Domestic Violence Hotline at 1-800-799-7233 (SAFE).