Why did Marion Jones go to jail while all these other male baseball players get off scott free?

Marion Jones, a black female Olympian, is now serving jail time after lying about doing steroids. While I don't condone what she did, I can't believe she is sitting in jail separated from her children while several male baseball stars have been caught in the same steroid scandal.Is there a different standard here? Why was Marion Jones made such a scapegoat? I don't think this offense warrants jail time.