Polokwane - A well-known Limpopo rhino farmer who was arrested by the Hawks in 2016 for allegedly trying to sell rhino horns has been murdered on his farm along with his wife, Netwerk24 reported. The bloodied bodies of Piet van Zyl, 68, and his wife Tilla, 66, were found on Sunday morning in their house in the Immerpan district near Roedtan. It is not clear if they were shot or stabbed to death. "There must have been a terrible struggle because there was blood everywhere," said a police offer who had been at the scene, but wanted to remain anonymous. It seems as if the attackers entered the house via the back door. Tilla was found in her pyjamas in the couple’s bedroom on the top floor. Piet was killed there as well. The safe was forced open but is not clear what was stolen. After farmers heard of the murders, they blocked the roads leading to the area in an attempt to catch the robbers. The police, in co-operation with the Heritage Protection Group (HPG), a crime fighting organisation, are searching for the killers. HPG trackers were following clear shoe sole prints in sand, but by Sunday afternoon, no arrests had been made. Tilla’s brother, Paul Maree, said the murders "show how vulnerable we all are". 'Enough is enough'Marcelle Maritz, the FF+ leader in Limpopo, condemned the murders. "We’ve reached a point where people must join hands. Enough is enough."Van Zyl was arrested along with Stephen Mylie and Marco Swanepoel from Pretoria during a sting operation by the Hawks on August 10 last year after they allegedly tried to sell five rhino horns to them. They then took the Hawks to a house in Equestria in Pretoria where three more rhino horns were apparently found. Hawks spokesperson Brigadier Hangwani Mulaudzi said in a follow-up operation, 105 more horns were found in the same house. Van Zyl claimed that the rhino horns legally belonged to him. He denied guilt on all charges. The Hawks had been set to confirm this and to find out, via DNA tests, if the horns had come from the poached rhino.Also read: Hawks sting nets game farmer over rhino hornsVan Zyl was freed in the Pretoria Magistrate’s Court on bail of R20 000. Mylie and Swanepoel are out on R10 000 bail each. Van Zyl in December was very upset when a rhino cow was killed on his farm. He said at the time: "I’m giving up. It can’t carry on like this, our animals are being slaughtered."He said the cow which was killed had been the tenth of his rhinos which had been killed. "All my animals have been dehorned, but the poachers are still so arrogant that they kill them. Why?"Tilla said at the time that four of their rhino had been killed for their horns on Christmas Eve in 2015. The couple had appointed armed guards to protect their rhino.