Has anyone else had any contact? I lost some BTC on that exchange way back in the day.
Was it PKF Corporate Recovery & Insolvency in New Zealand who contacted you? If so, it may be legit.
I stumbled across this case recently when looking into outstanding Mt. Gox claims. The stolen Bitcoinica funds were found in an Mt. Gox wallet before Gox went down. PKF has supposedly been trying to recover those funds on behalf of customers through an Mt. Gox claim.
Their website lists this under "recent notable appointments":
http://www.pkfcr.co.nz/services/
I would contact them directly. Maybe they are contacting claimants in relation to the recent Fortress offer?
Yep, that's them.
I didn't want to hand over my information to them not knowing what they were doing because I figured that if I hand them my proof of claim then if they were just scammers they could take my proof to the real lawsuit.