Matherly walked into the bank, according to detectives, told a teller she had a weapon and demanded money. Matherly then left the bank with an undisclosed amount of cash, investigators said.
"These individuals robbed several banks across the country. They have been successful, not only in Illinois, but Florida, Tangipahoa Parish and ultimately here," Strain said.
Investigators also found the couple's two small children. They are now in the custody of the Louisiana Department of Children and Family Services.
"It's not unheard of for people to do incredibly ignorant things with young people or kids, but it's a first for me that I've seen an actual bank robbery committed with very small children involved," Strain said.
Both Matherly and Davidson are from Kankakee, Illinois.
"Whether you define them as a modern day Bonnie and Clyde or what have you, that appears to be the only gameful employment that they had was robbing banks," the sheriff said.
Bank personnel were able to get a description of their vehicle, a 1995 Cadillac DeVille, and a Florida license plate number, investigators said.
"Our deputies understand that there are so many avenues that a potential robber can take and we do everything we can to restrict those avenues," Strain said.
According to Strain, deputies closely watched and patrolled the major highways in the area, before a deputy spotted the Cadillac on Hwy. 21 near Bush, roughly 13 miles from the Citizen's Bank.
The couple turned off Hwy. 21 onto Woodcock Lane, which is a dead end. Deputies arrested the couple there.