Tad Cummins, ex-teacher suspected of kidnapping student, may need medication, left note for wife Tad Cummins, 50, is accused of kidnapping Elizabeth Thomas on March 13.

 -- Pharmacists have been asked to be on alert for the Tennessee teacher who allegedly kidnapped his 15-year-old student because the 50-year-old, who has been on the run for nearly one month, likely needs a refill of his blood pressure medication, the local district attorney said.

Tad Cummins, a married father and grandfather, and 15-year-old Elizabeth Thomas have been missing since Cummins allegedly kidnapped the teenager on March 13. Surveillance images showed the pair at a Wal-Mart in Oklahoma City two days after they disappeared, but there have been no other credible sightings.

Brent Cooper, the district attorney for Maury County, Tennessee, told ABC News on Tuesday that Cummins is on medication to control his blood pressure and should need a refill, so pharmacists should be mindful of customers who look like Cummins or Thomas.

Cooper also told ABC News that Cummins left a note for his wife the morning he vanished. Cooper didn't provide details on what was in the note, but said it appeared to have been a diversion to throw investigators off the trail.

A lawyer for Cummins' wife, Jill Cummins, said that she has filed for divorce.

Tad Cummins, who was fired one day after the alleged kidnapping, is wanted on allegations of aggravated kidnapping and sexual contact with a minor. An Amber Alert has been issued for Elizabeth.

The Tennessee Bureau of Investigation has said that Tad Cummins "may have been abusing his role as a teacher to groom [the teen] ... in an effort to lure and potentially sexually exploit her."

One of Elizabeth's schoolmates reported seeing a kiss between Tad Cummins and Elizabeth in his classroom on Jan. 23, according to a school district investigative report, but both denied the claim. A school report from January stated that neither one "admitted to behaving inappropriately towards the other."

According to law enforcement officials, Tad Cummins researched teen marriage online, specifically the age of consent.

Authorities are asking that anyone with information call 1-800-TBI-FIND and that anyone who sees a car with Tennessee license plate number 976-ZPT call 911.

ABC News' Eva Pilgrim, Lauren Putrino and Glenn Ruppel contributed to this report.