Mannheim (dpa / lsw) - Three men have been in custody since Wednesday on suspicion of joint manslaughter. According to investigators, the men, aged 20, 23 and 49, are said to have killed a 42-year-old man. His body was found in an apartment in Mannheim on Monday evening. The victim showed blunt force marks. The dead man was discovered by an employee of a personnel service company that employed the dead man. The suspects, all three are Polish nationals, were arrested on Tuesday by special forces in the Stuttgart and Herford areas (North Rhine-Westphalia). The background to the crime was still unknown.