In a suicide note found in his locked desk, a South Carolina restaurant lobbyist who shot and killed himself in a parking garage called himself "a huge disappointment" for not discovering the theft of agency funds sooner.

The three-page, handwritten note left by Tom Sponseller does not directly state who stole as much as $900,000 from South Carolina Hospitality Association's coffers, but it seems to point the finger at an employee already named by federal authorities who are probing the theft.

In the note, obtained by NBC affiliate WYFF-TV, the 61-year-old Air Force veteran describes Rachel Duncan, who authorities have called a person of interest, as "like a daughter" to him.

"It is quite disappointing that all the work our members and staff put into building one of the best associations in the state has been jeopardized by the stupid actions of one person and not detected until the amount was so large the police found it first because I had failed to make sure everything was right," Sponseller wrote.

"I am sorry it ended like this," the note continued. "I am a huge disappointment to everyone, my family, my friends, business associates and others. I let everyone down and have embarrassed those who I love the most, my wife, kids, and grandkids. I am so sorry I have failed you. Please find a way to forgive me in your hearts."

Duncan has a history of financial troubles. She filed for bankruptcy in 1998 and has been charged three times with submitting bad checks, and her home is currently being foreclosed on. She and her attorney Greg Harris have refused comment.

"Ms. Duncan has been interviewed, and she is a target of our financial crime investigation," U.S. Secret Service Special Agent in Charge Michael Williams told The State newspaper.

Sponseller, who was missing for nearly 11 days before being found in a locked room off a parking garage at association offices, is believed to have shot himself in the head, according to Richland County Coroner Gary Watts. A 9-mm handgun was recovered at the scene.  

His Mercedes sedan was found parked in the garage near his office, and no signs of a struggle were evident. His cellphone and wallet were missing. 

Duncan had no comment Friday when approached by Fox News outside her home in Lexington. 

Sponseller is a Citadel graduate and a former Air Force officer, according to his biography on the South Carolina Hospitality Association's website.

Fox News' Mary Quinn O'Connor contributed to this report.