New Delhi: The Enforcement Directorate has arrested four persons including the MD of the Lava International mobile company and a Chinese national as part of its ongoing money-laundering probe against Chinese smartphone-maker Vivo, official sources said on Tuesday. They identified the four as Hari Om Rai, the MD of Lava International company, Chinese national Guangwen Kyang, Chartered Accountant Nitin Garg and a person called Rajan Malik.