Cape Town - "Your mother is calling you!" is a shout commonly heard as neighbourhood children play a quick game of soccer or squeeze in a few touches down the road as supper gets ready.Not wanting to incur the wrath of mom, children reluctantly leave the game and often walk home with the person delivering the message, trusting them completely.The mother of slain Cape Town 11-year-old Stacha Arends says parents should start using the code word system with their children to ensure that they are not lured away from their friends and then abducted.Sandy Markgraff believes that her child was lured away from a friend's house in March on the pretext that she was looking for her.Randy Tango, the man accused of kidnapping, raping and killing Arends, is believed to have lived in the same area as the friend."Make it a secret word that only you and your child know," said Markgraff on the side-lines of the appearance of Tango at the Western Cape High Court on Friday."If you send someone to fetch your child, tell that person the code word," said Markgraff. "And tell your child not to go with them unless they say the right code word."Support systemShe advises parents to drum it into their children's heads that they should never walk away with somebody who does not know this secret word, no matter the circumstances or how well they know them."And you must change it to a different one every time it has been used," she said.On the day of her disappearance, Arends had been watching television at a friend's house. When the friend returned from the toilet, Arends was gone.After a search, Arends' body was found in a bushy area near a sports field the following day.Markgraff believes the only way to help prevent the kidnapping of children by people familiar to them is by encouraging the code word system.She said if it was not for her family, she would not be able to get out of bed every day after Arends' death.Markgraff is one of many parents grieving the violent deaths of their children in the Western Cape this year. The families have formed tight bonds with each other, and support each other during the difficult court appearances.As she spoke, friends who had come to court hugged her and offered words of encouragement.