Tumbleweed has announced the appointment of its third CEO in just six months.

The security company's new head is James P. Scullion, hired from ComnetiX after previous CEO, Craig Brennan, resigned last week. Brennan himself replaced Tumbleweed co-founder Jeff Smith, who stepped down from his job in the summer of 2005 after 12 years in the post.

It is not clear why Brennan left, but his departure was only formally announced this week. The delay in the announcement suggests that the appointment of Scullion was not in place when Brennan resigned.

The official press release announcing the new CEO, omitted any of the pleasantries usually given to outgoing heads. At the time of his appointment, Smith said of Brennan, "I’ve been committed to ensuring that we find a new CEO who has just the right combination of experience, acumen and leadership. With Craig’s appointment, I’m confident that Tumbleweed is in very capable hands."

The new man in the hotseat brings plenty of experience to the job, having been the CFO of DataTrak; before that, a biometric specialist Identix for 12 years. More recently, he was CEO of a company called ComnetiX.

Tumbleweed presented to a closed session of investors on 10 January in Massachusetts, a day after it is believed the departed CEO Brennan resigned. The company has so far refused to expand further on the reasons behind the CEO shift.