E-mail Got Hacked

My colleague e- mail was hacked by an unknown person.He was move to Italy for a couple months .He always keep in touch to his workmates.His good friend receive an e-mail from him asking a favor to send 10 pieces of mobile cards and pay it through money transfer so my workmate buy and send the cards after work.Then she send an e-mail using company mail to inform that she already text the card numbers.The later got shocked!His three friends from Philippines complain him about the payment of the cards.They believe that it was really him because of the pictures.The hacker also use the yahoo messenger to explain and give instructions clearly in sending the card number and with web cam showing the image of my colleague.Who would be blame here? nothing...maybe that image is only recorded.Let's secure our e-mails now!