RUSTENBURG, South Africa (Reuters) - The chanting began around midnight, a chilling message through the cold of the early South African winter to those who had dared to cross the picket lines at platinum producer Lonmin.
"The rats must come out of their holes. We are going to kill this NUM," the crowd chanted as it approached the home of 'Mary', a member of the National Union of Mineworkers (NUM) who had kept working at Lonmin when the rival Association of Mineworkers and Construction Union (AMCU) was on strike.
Her real name cannot be revealed because she fears for her life.
"I heard singing in the distance. I thought I was actually dreaming, but it was getting nearer and nearer," said Mary, who spoke to Reuters at an undisclosed location.
The events she related unfolded outside her home near Lonmin's Marikana mine on May 14, which the London-listed company had declared a "return to work day" in the hope of persuading enough people to end the crippling AMCU strike.
The 17-week stoppage, which has also hit Anglo American Platinum and Impala Platinum, did not end that night; AMCU members blocked roads, extending the longest and costliest industrial action in South African mining history.
Fear is proving a potent weapon for the AMCU as it holds out for wage increases that the mining houses say they cannot afford.
Four NUM members were hacked or beaten to death in the run-up to May 14, and when Mary overheard someone at work - an AMCU "spy", she feared - muttering "we must remove her head", she thought she could be next.
A fifth NUM member was stabbed to death on his way to work at an Anglo American Platinum mine on Thursday.
When the crowd of 50 men in green AMCU t-shirts gathered at the end of her street - most carrying clubs, others scythes - they chanted the names of NUM members.
"I live in a circle, like a dead-end street. They stood there and they started humming and saying that the rats must come out," Mary said, still shaken as she recalled the moment her three daughters, the eldest 13, awoke to the noise.
"Then they started pointing at the houses because most of us NUM people live in that street. I've got three children. They were all at home, and they were traumatized."
Mary's husband was also there, but he is a mine supervisor and not an NUM member, giving him some degree of cover. "I'm the one who's a target because I am an NUM member," Mary said, still wearing blue overalls after a day shift.
Eventually the crowd drifted away to join a larger group marching around the mine in their bid to prevent workers breaking the strike, but not before its message had sunk in.
NUM sources say the union now has 15 members living in safe houses around the platinum belt town of Rustenburg, 120 kilometers (70 miles) northwest of Johannesburg. They go to work under the protection of private security guards.
AMCU denies it uses violence and intimidation, and police have made no arrests in connection with the five recent murders, but on May 14 thousands of AMCU members stopped others from returning to Lonmin's shafts.
Reuters journalists at AMCU rallies in Marikana have also routinely heard members chanting "What is this NUM? We must kill this NUM."
At such gatherings, AMCU members often greet the media with hostile stares or refuse to speak to reporters.
AMCU emerged as the biggest platinum union in 2012 after poaching tens of thousands of NUM members in a turf war in which dozens of people were killed.
It, too, has lost members, not least when police gunned down 34 wildcat strikers at Marikana in August 2012, the bloodiest security incident since the end of apartheid in 1994.
Since then, NUM says 46 of its members have been murdered, and even though 40 arrests have been made, police have secured no convictions, and suspects accused of violence have often been released on bail, General Secretary Frans Baleni said.
"We have seen cases where the police do not act, and if they do act, the justice department fails and people get bail," he told Reuters.
A police spokesman said they knew the ring leaders behind the latest wave of intimidation but have made no arrests. He did not explain why.
AMCU leaders have tapped a deep vein of discontent among black miners who feel they are still not getting a fair share of South Africa's mineral wealth, making its fight an extension of the struggle against the continuing inequalities that are a legacy of apartheid.
Its charismatic president, Joseph Mathunjwa, frequently portrays the strike as an all-out battle against injustice, the "platinum cabal" and the "capitalists". Strike-breakers such as Mary are painted as sell-outs to the forces of oppression.
"Even though I am in a safe house now, I still get nightmares. I'm on sleeping pills and anti-depressants. I get anxiety attacks," she said, adding she may be forced to quit and move back to her native Eastern Cape.
Although she said she loved her job, it was not something she was prepared to die for.
"I love my kids more. I love my life more."
Editing by Ed Cropley and Will Waterman