South Korean prosecutors have requested an arrest warrant against Samsung Group heir Jay Y. Lee and two former company executives, they said on Thursday, in an investigation of a controversial 2015 merger and alleged accounting fraud. The move spells fresh legal trouble for Lee, who already faces trial on a charge of bribery aimed at winning support to succeed ailing group patriarch Lee Kun-hee, and which involved former President Park Geun-hye. Samsung declined to comment.