Recently I purchased a large number of coins on an exchange and began to proceed to send them to a private wallet. I had $5000 stolen within about 20 minutes of my first deposit. I had followed the same procedure I have used for years without incident, downloading an offline generator, booting a machine with TAILS..........
There is something wrong with this, you say you followed this for years and yet your coins were lost. Were you using it on a public wifi as many people have lost it using public...........
What's the exchange name, post your address of funds, and the address where funds went.
He's using TAILS(live version i believe), so chances of virus infection is very low. it's probably the offline keys generator that he used must've stolen the money. op can you share which offline generator were you using? sorry for your loss.