Another departure at Motorola (NYSE: MOT). CMO Kenneth “Casey” Keller Jr.—hired in October 2006—to reinvigorate the brand, left last Friday, reports the WSJ. The handset maker said Keller’s job was being “eliminated”, and marketing at the company would now be overseen by two executives who formerly reported to Keller: Jeremy Dale, now head of marketing for mobile devices, and Eduardo Conrado, VP of business and technology marketing and communications.

Keller’s departure comes at an increasingly tumultuous time at Motorola. Since CEO Greg Brown took over in January, the beleaguered handset maker has seen an exodus of high ranking staff, including its CFO, CTO and head of HR and analysts are predicting that Keller won’t be the last. Motorola announced this week that it was currently looking for a new chief for its mobile devices division. If that weren’t bad enough, it looks like the company will have to deal with another proxy batter with activist investor Carl Icahn, who wants the company to hive off its mobile handset division. In February, Icahn nominated four executives for the company’s 13-member board, and yesterday, it an SEC filing revealed that he had increased his stake in Motorola to 6.3 percent from 5 percent. On Wednesday, Motorola urged shareholders not to vote for Icahn’s nominees. Icahn lost a proxy battle last year in which he was seeking a seat on the board.

• Icahn Ups Stake In Motorola To 6.3 Percent; Proxy Fight Looming?