NEW YORK – An undercover investigation by a prominent human rights group has found labor rights violations ranging from unpaid and excessive overtime to verbal and physical abuse at a China-based supplier to Samsung. The report, issued this week by China Labor Watch, details such violations as $84,000 of monthly unpaid overtime wages, up to 148 hours of overtime per month, intense rates of work that have workers assembling one cellphone case every four seconds, regular verbal abuse by management, forcing workers to work barefoot, fines imposed on workers, and insufficient safety training and safety measures.