Our head of R&D suddenly stopped coming to work in the middle of last year. After some weeks he was replaced by a new member of staff who took over his role, but the company made no announcement about what had happened to his predecessor. Some months later I heard through the grapevine (mir hat es jemand zugezwitschert) that he had taken a job with a competitor in China. He had also stolen the technical plans for the major new product development he had been working on and given them to his new company.
This idiom is of course best known from the old Motown song by Gladys Knight & the Pips, which was later covered by Marvin Gaye,