Neither side would give details but both said the parting was amicable.
Marsh officially left Odgers just before Christmas and is considering various options. He moved to Odgers a little over two years ago from TMP Worldwide.
His role has been taken over by Geoffrey Forester, a principal and senior partner who came from Ray & Berndtson, the technology-dominant US search firm that merged with Odgers.
Last year the technology practice at Odgers Ray & Berndtson is believed to have contributed about 4m (€6.4m) to total revenues of 20m. It is regarded as being among the leading technology search practices in the UK.
Odgers recently also launched a fledgling biotechnology practice. Its financial services practice has grown from a small base through organic growth and acquisition of the Berwick Group last year, and its board and industry work remains a strength.