charges/ a charge

[sky3120]

"He decided to step down to take responsibility for the ongoing investigation into charges that he gave cash to fellow lawmakers during a party leadership convention in 2008".

"into charges that he gave cash to fellow lawmakers during a party leadership convention in 2008".


When I studied English, I found this sentence but why "charges" was written instead of "a charge although just one case is followed?

I found not only charge but also plan is written in a form of plural, breaking the rule of number agreement. Is there a reason and meaning difference between singular and plural in this case?

Thanks and sorry to take your time but help me again.

[SoothingDave]

There can be multiple criminal charges based on just one act of wrongdoing.