When Ziegler took longer than the kidnappers anticipated, they abandoned the plan and released their hostages unharmed in Knoxville's Gettysvue Country Club parking lot. They fled the scene without the money.

On July 7, 2015, a SmartBank employee and his family were kidnapped from their home and held hostage at gunpoint.

The employee and his family were taken to a SmartBank branch in Knoxville where the employee was coerced to remove an undisclosed amount of money, which was provided to the robbers.

The employee was then left at the bank and his family was released unharmed a short time later, according to the FBI.

About a week after the Y-12 FCU attempted robbery, the FBI released a description of the suspects. The two males were white, one was between five feet, nine inches tall and five feet, 11 inches tall with a thin build. The second suspect was described as five feet, 10 inches to six feet tall with a stocky build.

These suspects in the Y-12 FCU incident closely match the suspects in the SmartBank robbery, according to the FBI.

“The investigative agencies are exploring the possibility that these two events are related, based on similar subject description and similar method of operation,” the FBI said in its prepared statement.

Federal authorities are also investigating a similar case that occurred on June 8 in Memphis, Tenn., when two black males wearing rubber masks, wigs and dark or camouflaged clothing kidnapped an FAA Federal Credit Union employee from her home at 6:20 a.m. and forced her to help them rob it, according to FBI investigators in Memphis.

Before leaving the home, the suspects tied up the employee's sister, leaving her there. Using the employee's car, the suspects drove to a branch of the $105 million FAA FCU and forced her to let them in the credit union to gain access to cash, FBI investigators reported.

After stealing an undetermined amount of money, the suspects drove off in the employee's car and later abandoned it behind a Kroger Supermarket about 1.6 miles south of the branch.

The Memphis FBI is also offering a $10,000 reward for information leading to the arrest and indictment of the persons involved in the FAA FCU robbery case.

The FBI has not said whether the Memphis and Knoxville incidents are related.

Federal investigators are also continuing to investigate the February home invasion and attempted credit union robbery case involving Matthew Yussman, CFO of the $121 million Achieve Financial Credit Union in Berlin, Conn.

Yussman claimed that two men disguised in dark clothing wearing ski masks and goggles invaded the home that he shared with his mother, strapped a bomb to his chest, and forced him to drive to a credit union branch to steal $1 million.

No arrests have been made yet in this case.