DEL MAR, Calif. -- With 25 victories, John Sadler is the leading trainer at Del Mar.

However, his rise to success is accompanied by some whispers of unethical practices.

Sources told 10News that Sadler's barn was raided by the California Horse Racing Board earlier this week. Investigators generally visit a trainer's barn after a drug sample comes back positive.

The board would not confirm or deny an investigation was under way.

Long-time horse trainer Howard Zucker said drug testing in the state is very strict.

"Penalties here are the most severe in the country. The testing here is the most stringent in the country," said Zucker.

Right now, many experts said the racing industry is in a period of transition. California is in the process of banning steroids, and the California Horse Racing Board started testing for steroids in July.

Trainers said it is up to the individual trainer's discretion when to stop using them.

"Some people chose to take their horses (off steroids) right away and some didn't. Of course it left the edge with the ones that are using it," said Zucker.

Starting September 4, any positive test for steroids is a state violation in which a trainer faces suspension, fines and might have to forfeit the horse's earnings.

In the meantime, many horse racing fans said everyone needs to be on the same level playing field.

"It makes it inequitable for people who are trying to do the right thing. Even though it's still legal it's still doesn't make sense that one person should have an advantage over another," said horse racing fan Stephen Post.

With the $1 million Pacific Classic just three days away, Post said he and his wife hope the race they are betting on is a clean one.

Sadler's attorney said his client has not violated any rules or regulations, and for now he is looking into the issue further.

Another leading Del Mar trainer, Jeff Mullins, could be facing a lengthy suspension after one of his horses tested positive for an elevated amount of carbon dioxide.

Beginning August 22, the California Horse Racing Board said it planned to step up enforcement when it comes to steroid use in horses.