Dozens of police officers and a detection robot were called to Arthur Street at 7.40 am.
Unsure what they were dealing with, investigators took no risks and shut down the entire surrounding block in Fortitude Valley.
“They just turned up out the front and stopped letting cars through,” witness Carl said.
Investigators used radar technology to determine what was inside the suspicious plastic case.
Police eventually uncovered what they described as a GPS tracking device.
“It is harmless and will be the subject of further examination by our scientific scenes of crime and local detectives,” Acting Inspector Gregeory Veivers said.
The object was discovered under a Black BMW and its driver Tom Rook, a well known Fortitude Valley property developer, is now covered in finger print dust.
It is understood he discovered a less sophisticated device near his car yesterday, claiming a disgruntled ex-girlfriend could be behind the placement of the tracker.
Read more at http://www.9news.com.au/national/2015/05/14/19/41/brisbane-bomb-hoax-may-have-been-caused-by-disgruntled-exgirlfriend#D17vbFEoM0TYfD1i.99