Police want to know what a trespasser on a bicycle was doing inside the ConocoPhillips refinery in Wood River on Wednesday evening
About 50 police and security officers searched unsuccessfully for the man for 11 hours after he rode past a security gate and into the facility at about 7 p.m. Wednesday. He was carrying a satchel.
They gave up the search at about 6 a.m. Thursday with no clues about where the man went.
Investigators found no damage to the plant which is capable of refining 157,000 barrels of crude oil per day.