"Anytime you have an internal fraud-type case going on, you want to be certain of the dollar amount," says Tyler Police Chief Gary Swindle.
Police were called at the beginning of July that the funds were missing. Hundreds of people come in and out of the court every day. And a lot of cash comes in.
"The degree of crime depends on the dollar amount, so we want to make sure that that amount is what we can prove in court -- which in turn, involves us going through a large amount of paperwork."
Swindle says the amount missing is "substantial."
Reporter: "Is it fair to say that it's in the six-figure range?
Swindle: "Well, I would say yes, it's very fair to say at this point in time, because that gives you a large range, but it's definitely it's over six figures."
Also, the investigation involves a long-time employee, who might have taken money over several years.
"You build trust in tenured employees, and sometimes, that's where the breakdown occurs," he says.
City Attorney Gary Landers told Channel 7, the city's investigation also involves how fraud could happen.
"We will consider which procedures we have for safeguarding money, and if they are enough," Landers says.
Court Administrator Cam McCabe says she couldn't comment on camera, but that the city will hide nothing.
Landers says, "When the investigation is over, everything will be shared with the public. The public has a vital interest in what was found."
Swindle says the probe is moving forward, with an arrest expected within a month.
An outside auditing firm is being brought in to look at the municipal court's accounting and safeguards, to prevent problems in the future.