Caught running
Here's a runner who wasn't supposed to be able to run. She had claimed a physical disability and investigators discovered her fraud.
Race directors may be contacted by insurance investigators searching for people who participated in races after filing workmens' compensation claims.
Employers may check on a person who ran a race after calling in sick. Others may want to verify a person's whereabouts on a particular day - when that person was supposedly somewhere else.
Since race results are usually publicized - online and in print - it's difficult for a competitor to hide. If runners ask you to omit them from the results, you don't have to comply. You may be abetting a fraud.
A race is a public event. If a runner doesn't want to be listed in the results, that person should not run.