The bodies of two Australian men and their American friend, who were shot dead while on a surfing trip in Mexico in 2024, were found by the United States FBI, a murder trial has been told.A Mexican court has also heard that a group of friends went looking for the men when they first went missing and were the first to find the camp where they were last seen.On day two of the trial into the murders of Perth brothers Jake and Callum Robinson and American Carter Rhoad, a colleague of one of the brothers revealed for the first time that the FBI had been "cooperating with Mexican authorities" on the case.The involvement of the American intelligence agency has not been made public before.The three men were believed to have been camping at a remote coastal area when they were attacked and shot dead in April 2024. Their bodies were later found dumped in a well.Jesús Gerardo, also known as "El Kekas", Irineo Francisco and Ángel Jesús are currently on trial in a small court in Ensenada, on Mexico's Pacific Coast.They have each been charged with aggravated homicide, aggravated robbery, violent robbery and grand theft auto.A colleague and friend of Carter and Callum, who asked not to be identified, told the trial that he had travelled with the two Australian brothers and the American on their surf trip to Mexico.The man said he returned home to San Diego early for work and became concerned when he texted Callum and Carter on April 28 and did not receive a reply.He then contacted the Airbnb where the men were supposed to be staying and was told by the hosts they had not heard from them.He told the court he rang Natalie Weirtz, the wife of Carter Rhoad, to inform her he was going to file a missing person's report.Callum (left) and Jake Robinson were keen surfers who followed their passion around the globe. (Instagram)The man told the court that Ms Weirtz was able to locate where Carter's phone had last pinged to a neighbourhood near Ensenada.The unnamed man told the court he and a group of seven other friends took it upon themselves to track down their friends.They drove to the neighbourhood where Carter's phone was last located. But the man claimed that when the group arrived, they believed it did not look like a neighbourhood where someone could safely knock on strangers' doors.They instead decided to drive to Punta San Jose, which is where the man believed Jake, Callum and Carter were planning to camp on April 27.It was there that he spotted what he described as the "black footprint" of what looked like a burnt-out tent along the bluff.The man said he immediately recognised a mug that belonged to Callum. Other items included a Birkenstock buckle and a glasses case that belonged to Carter Rhoad.The group also found what they assumed to be blood and a shell casing. Mexican authorities identified it as a crime scene.The man said he was told in the following days that the bodies of his missing friends had been found. The ABC asked local Mexican authorities to confirm the involvement of the FBI, and they refused to comment.Parents don't hold 'animosity' towards killersThe Robinson parents have travelled from Perth to Mexico to attend the trial in person.Debra and Martin Robinson travelled to Mexico so they could be in court for the trial. (AFP: Guillermo Arias)In testimony lasting more than an hour, Martin Robinson told the court about the timeline of his sons' disappearance and the discovery of their bodies."I'm here because my two sons were murdered," he told the court.He recalled receiving a phone call on May 1 from an American phone number that he had initially assumed belonged to Callum because it was his birthday. It turned out to be a friend of his son telling him the brothers were missing.Mr Robinson said he and his wife, Debra, left Perth to fly to America two days later. When they arrived in Tijuana, they met with the attorney-general and were asked to identify their sons' bodies.Martin Robinson identified Callum by his tattoos and Jake by photos of his face. He then provided DNA and blood samples, birth certificates, and a registration certificate for Callum's pickup truck in order for them to match the bodies."We don't hold any animosity against the people who did this, but what we don't understand is how they could rob the world of two beautiful men who had such bright futures," he told the court during his testimony."We miss them every day, and our lives are never going to be the same again."Callum Robinson's Instagram shows a man who loved sports, the beach and his family. (Supplied: Instagram)As he got up from the stand, his wife, who had been quietly crying in court as he spoke, whispered some words of encouragement before they embraced.Ms Robinson was called to the stand yesterday but only identified herself before the prosecution said her testimony was not necessary.Carter's mother says killing looked like 'an execution'The mother of Carter Rhoad, Page Rhoad, also gave testimony at the trial, appearing via videolink in court from her home in the United States.She testified that she had been told her son and the two Australian men had been shot "three times". The autopsy for the three men has not yet been revealed in court.In a similar account to the one given by the unidentified friend of Carter and Callum, Ms Rhoad also discussed how a search party was assembled to go to Mexico to look for the missing men.Baja California is one of Mexico's most violent states. (Supplied: Abraham Galvez)She said the group of eight, which included one of her sons, gathered at Ms Weirtz's house in the south of San Diego, before they got into two separate cars and crossed the border.Ms Rhoad said she and one of her daughters then decided they would travel to San Diego. On May 3, they met with the FBI and were told bodies had been found in a well. The next day, she was told those bodies were believed to be Carter, Jake and Callum.Ms Rhoad said she travelled to Mexico to help identify her son's remains. When she looked at photos of the body, she said she recognised her son straight away."I'm not an expert, but to me it looked like an execution," she said of seeing the bodies.She went on to describe Carter as an "amazing son" who was looking forward to holding a public ceremony with his wife, whom he had secretly married in December 2023.The case against the accusedThe prosecution has outlined a case consistent with previous public comments about a robbery gone wrong, although defence teams have claimed in court there is not sufficient evidence to prove the theory.On the first day of the trial, a judge ordered the removal of the three defendants from the courtroom after the prosecution said two witnesses had been intimidated by people connected to the accused.The three men were returned to the courtroom for today's session.Ángel Jesús (surname suppressed) may never be released from prison if he is convicted. (Supplied)The prosecution is seeking to have Jesús Gerardo sentenced to additional jail time. (Supplied)Irineo Francisco was the fourth person to be charged in relation to the killings. (Supplied)Yesterday, the court heard from two witnesses: one was the former girlfriend of El Kakas, and the other was her adult son. They are both in witness protection.The man, whose name was withheld, provided an account of what took place on the day the Australian brothers were murdered, while his mother testified about her relationship with El Kakas and his alleged domestic violence.Ari Gisell, another ex-girlfriend of one of the men now on trial, was sentenced to 20 years in jail last year for her role in connection with the murders.The prosecutor had argued Gisell was the instigator of the attack on the tourists because she had expressed interest in the tyres of the car they were driving and their phones.