I've contacted. I've found out how the attacker obtained my Gmail account credentials, and then my Blockchain.info account credentials. The attacker then logged in from a public WiFi in England to steal the funds. The attacker visited my Gmail first. The attacker took ten minutes on my Gmail, and searched for "bitcoin, identifier, mnemonic" etc. The malware PUP.Optional.Goobzo came from a malicious website. I don't know which website this is, but it could be any website. I normally search tech topics, and the naughtiest things I do on the Internet are Pornhub and even Cryptocoinsnews. It is possible that some of the administrators of these sites run malware. This problem should be fixed by cookie settings. Do not accept cookies except from whitelist. My browser history only shows the authentic link, so I've not visited a phishing site. The malware has been on my computer for some days. So, the attacker knew to wait for the transaction, and likely had access to my computer. From now on, I will not recommend Windows OS for Bitcoin users. I have Linux on the other computer. I will also use paperwallets and Airbitz as a hotwallet. Thank you.