Need help wrt Documents

External ministry - only passport because that's what they issue

Indian consulate - absolutely nothing if person has not registered with them and really no one does in america and europe as they are useless guys. only in Gulf labor does...

Only way  you have file RTI to income tax department, if he is maintaining NRO accounts or investment accounts MF or shares, tax will be getting dedcuted, remember NRO accounts not NRE. Once you get infomration that from where tax deducted you can ask court to summon bank manager with records of account. But you need PAN number and NRO/Investment account should be maintained. Otherwise if you have PAN number try in desi way different banks where he is remitting money and than call bank manager.

But this wil not prove his current earnings and may not be helpful.