You Can’t do that. Seriously
You can’t use backdoor contacts into the candidates current employer because you “know someone” to find out their current pay and personal information.
You can’t make a low offer based off their current mid level position when your role is a global, niche’, high stress role with average 60 hour weeks to completely set up your new program.
You can’t call a candidate a untrustworthy when they ask for a fair salary for the role you were hiring regardless or their current compensation, especially when they were asking 17% below market to begin with.
You should however be ashamed of yourself for being dishonest and illegally acquiring information that you should never have pursued