The FBI has released a photo of the bomb threat that forced about 170 passengers to evacuate a flight leaving from St. Pete-Clearwater International Airport in April. The message was written in blue ink on the inside of the plane's bathroom door. "Bomb on flight check cargo," it reads, with "all allegiant flight" written in smaller letters underneath it. The bomb threat was discovered on April 25 on Allegiant Air Flight 2006. Pinellas County Sheriff Bob Gualtieri said the flight had just landed at St. Pete-Clearwater International Airport from Cincinnati and was set to turn around quickly and return to the city. But after the passengers boarded the flight and the plane had taxied away from the gate, a flight attendant opened the bathroom door and saw the bomb threat. They alerted the pilot, who stopped the plane and evacuated the passengers. The sheriff's office responded with bomb dogs that searched at least six Allegiant planes at the airport. "We found no evidence of any explosive devices," Sheriff Gualtieri said. At the time, the sheriff said investigators were focusing on one person whose "actions were suspicious." Now, the FBI's Tampa Field Office is asking for the public help identifying the person who wrote the bomb threat. Anyone with information on the case is asked to contact the FBI's Tampa Field Office at (813) 253-1000 or submit a tip online at tips.fbi.gov.