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A fourth person has been arrested over the alleged murders of Perth brothers Jake and Callum Robinson who disappeared earlier this year in Mexico.
9News can reveal a man has been arrested in connection to their alleged murders a month after the brothers' bodies were found 10 metres down a well.
Authorities did not provide any further details or the identity of the man.
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The Robinson brothers disappeared with their US friend, Jack Carter Rhoad, during a surfing trip in the Baja California on April 27.
The siblings, aged 32 and 31, were found weeks later near their remote campsite and three Mexicans were soon arrested.
It's believed the brothers were shot dead in a "robbery gone wrong".
Two of those arrested were caught with meth and one of them, a woman, had a victims' mobile phone on her.
The accused ringleader of the Mexican trio, Jesus Gerardo, also known as El Kekas, faced court and will remain behind bars until his next hearing in November.
Attorney General Maria Elena Andrade Ramírez said it is believed the brothers and Rhoad had been killed during an opportunistic robbery attempt.
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But the execution-style killings raised suspicions there could be links to organised crime.
The Robinson brothers were laid to rest earlier in June as hundreds of people gathered to pay tribute at their former high school Sacred Heart College in Sorrento.
Their parents, Debra and Martin Robinson, reflected on who their sons were before their lives were heartbreakingly cut short.
"Callum and Jake meant so much to us and it's still hard to imagine life without them," Debra said at the memorial service.
"They were intelligent, respectful men and they had so much more to offer the world.
"They loved life and they followed their dreams."
