Police know who they are looking for and are circulating a picture of the suspect.
Before leaving the garage, CTA drivers are supposed to show their driver's license to the garage clerk. They are also supposed to be in uniform and display their CTA identification at all times. Somehow the suspect was able to circumvent those rules.
The suspect was apparently wearing a stolen uniform and knew what he was doing well enough to be able to get behind the wheel and take a bus out on the street.
"As part of the investigation, identifying where the bus was at, what it was doing, but it doesn't appear to be doing anything random, just basically going down the street," said CTA President Rich Rodriguez.
Along the way the suspect stopped to pick up and drop off numerous passengers who apparently never suspected they were on a stolen vehicle.
He took the bus out at 8 p.m. last Thursday night and returned to the garage about midnight.
But, when parking the bus, the suspect scraped another vehicle, which prompted an employee to report him to a supervisor. That's when the suspect ran off.
Police believe they know who he is.
"We have a person of interest that we're looking for...we've identified this individual. However, it is an ongoing investigation," said Cmdr. John Graeber, Chicago Police, mass transit unit.
Some frequent bus passengers say they are concerned.
"If someone who is not a CTA driver is riding around, then that could create a lot of chaos," said CTA rider Stephanie Fernandez.
Investigators believe the suspect is an acquaintance of a CTA employee who reported his uniform stolen several weeks ago.
And while they are relieved he apparently caused no major disturbances, they say they are deeply concerned about the breech in security, and they still have no idea why he did it.
"Until the police department is able to bring this person in and try and find out what they were thinking and why they would want to do something like this, we still have some unanswered questions," Rodriguez said.
As a result of this the CTA plans to tighten the check-in procedures for drivers. They also plan to lock all the garage doors overnight other than the entrance the buses use.
The CTA president says they plan prosecute the suspect to the fullest extent possible.