The suspects kidnapped Ziegler, his wife and their teenage son, and demanded that Ziegler go to the credit union to retrieve an undetermined amount of money to secure the release of his family.

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.

The first sketch (pictured above) outlines the facial features of a white man in his early 30s with long brown hair, a round face and a heavy build. The FBI said he is a person of interest.

The second sketch (pictured at left) is of a female in her 30s with pale white complexion, thick lips and long black hair, which possibly was a wig.

The third sketch (pictured below) is of a male in his late 20s or mid 30s whose facial features are covered. However, the FBI identified him as having an orange tattoo with a black or blue outline on his neck and possibly salt and pepper-colored hair.

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.