Need clarification about disputing with OC about inaccurate information

[notmine77]

I've got a negative mark on my credit that should not be there. It first showed up only on Experian, and when I disputed it, it came back "verified." Then, AFTER that, it showed up on the other two CRAs, with the note that I had disputed the information.

My question is about one of the finer points of Section 623. My understanding is that I should dispute with the OC only after disputing with the CRAs. However, I only disputed with ONE CRA, because at the time it was the only one reporting it. The other two began reporting it after the dispute was "verified."

So...am I clear to dispute with the OC? Or do I now need to dispute with the other two CRAs first?

[OU812B4]

Dispute with the other 2 CRA's first and wait for the results. If those also come back as verified send a letter to the OC requesting an investigation.