This used to be my favorite.
Who is liable for the transaction is 100% irrelevant. He's already said "fuck you" by pulling this and told a story he can't easily retreat from.
My way of dealing this with cams was simple.
I would write them back, ignoring the "my son...." part and just act as if someone stole ther card as if it happened and we need to get people arrested for it.
(On my iPhone - so I can't type it out as a really well written response)
Dear Sir,
We recieved your message regarding the theft of both your credit card information and identity. Though this happens quite frequently online, I want you to be assured that we investigate and report every instance of these crimes to all local, state an federal authorities and will cooperate fully to bring the perpetrator of this act of fraud to justice.
We would greatly appreciate it if you wcould assist us in our investigation and confirm all of the relevant details so that we may forward everything to the appropriate law enforrcement agencies.
As we understand, someone gained unauthorized access to your personal computer at IP address zzz.zzz..z.zzz an then ypur personal email account which is "
[email protected]" posing as you on the date of....? Unfortuneately, these are common acts of identity theft, computer fraud, wired fraud and so on, all in violation of Federal Law and State law.
This individual further used your MasterCard, ending in 2210, posing as you to make a fraudulent purchase of $xx,xx?
This individual then gained access to the websites
www.teensassfucked.com with the fraudulently obtained username and password using your identity and credit card?....
Anyway you get the point. The next respnse is a typical panic email saying its ok, he'll deal with it etc.
I would usually reply again that we appreciate his cooperation and look forward assisting law enforcement in investigating these crimes committed against him and so on (again ignoring any referrence to his kid and attempts to just say "let'sjust forget about it"). I had this happen a lot in cams for very large amounts at times and never had anyone using the "my son did it" excuse charge back once I was done fucking with them.