Up to 4,000 workers at the Marikana platinum mine in South Africa -- the scene of deadly violence in August -- returned to work on Friday after downing tools a day before, managers said. \"All Lonmin employees who were engaged in work stoppages on Thursday 18 October are back at work,\" the Lonmin mine said in a statement. \"Normalisation of operations is progressing well and is ahead of expectations.\" Some miners refused to go underground on Thursday, protesting reports of police harassment after four men were arrested in the last week. Police spokesman Thulani Ngubane confirmed the arrests, carried out since last Friday. In the latest detention a man local media identify as Xolani Nzuza, leader of the six-week strike, was arrested on Thursday. Authorities suspect him and another worker of \"killing their co-workers during the ugly Marikana unrest,\" said Ngubane. In all 46 people were killed, both workers and police, over weeks of violence that are now being investigated by a government-appointed commission of inquiry. At least 11 of the deaths were at the hands of strikers. The panel, led by a retired judge, is expected to resume deliberations on Monday. Meanwhile two men were arrested and appeared in court for shooting dead Daluvuyo Bongo, 41, local branch secretary for the powerful National Union of Mineworkers (NUM). Bongo was killed on October 6, days after giving the inquiry a guided tour of the mine area. Employees at the mine have been back at work for almost a month, after the worst violence seen in post-apartheid South Africa prompted management to agree a substantial pay rise.