Preston's exit yesterday (12 June) follows the departure of Morrin, Kaspersky Lab's director of European business events and exhibitions, earlier this year.
Preston, who has previously worked for IBM, joined Kaspersky in August 2012. Morrin joined in May 2013 from Active Network, now Lanyon.
In an email, Preston said: "I have decided to leave Kaspersky after nearly two years. It has been a fantastic journey. I have made some great new friends and worked with some very talented people but sometimes you just have to follow your passion.
"I will be pursuing a role, back in the events industry, which many of you will know, is my background and true passion."
This also follows the news that Kaspersky has slashed its events budget by 50% in 2014.