Authorities are investigating a mysterious tip on an 11-year-old girl’s disappearance that showed up on a dollar bill in Wisconsin.

Someone handed over the dollar with the mysterious message to authorities on March 14 in Neenah, Wisconsin, and authorities are now investigating the dollar bill to see if the message could lead to a breakthrough in the missing girl’s case, the Arizona Republic reported.

“My name is Mikel (sic) Biggs kidnapped From Mesa AZ I’m Alive,” the message on the dollar bill reads.

The girl, Mikelle Biggs, disappeared more than 19 years ago after she was waiting for an ice cream truck with her sister in Mesa, Arizona, on January 2, 1999. Her missing persons case drew national attention—including a 2009 ABC News television special on the unsolved case called Vanished: Gone in 90 Seconds.

Neenah Police Investigator Adam Streubel said he examined the bill, but expressed doubt over the message’s authenticity because the girl’s name on the bill is misspelled.

“There’s no way to trace it,” Streubel said, adding that it is “impossible” to track the number of people who have touched the dollar bill over the years or how the bill got to Neenah.

“There was a little spring of hope for a second, and then reality set in,” he said. “There is nothing you can do with it, which is rather frustrating.”

Even though Streubel said he was not familiar with the kidnapping case, Mesa detectives got wind of the tip on Monday and plan to use the mysterious note on the bill as evidence that could help the case along.

Mesa Police spokesman Detective Steve Berry told the New York Daily News that detectives learned of the dollar bill Monday morning and are investigating it.

“Anytime we get new information that may resolve this case and give closure to the family and community, we make every effort to validate or invalidate the lead,” Berry said.