A former Royal Marine commando who was charged with spying for the Hong Kong intelligence service has died, police have said. Matthew Trickett, 37, who was on bail, was found by a member of the public in a park near where he lived in Maidenhead, Berkshire. Thames Valley police said officers attended and administered emergency treatment but he was pronounced dead at the scene in Grenfell Park on Sunday. The force said: “An investigation is ongoing into the death, which is currently being treated as unexplained.” Trickett appeared in court along with two other men last week accused of monitoring, surveillance and harassment of pro-democracy activists in the UK. His profile on LinkedIn lists him as being a former Royal Marine commando. He was in the marines between 2007 and 2013. Trickett was a Home Office immigration enforcement officer and also ran a private security consultancy. Trickett, Chung Biu Yuen, 63 and Chi Leung “Peter” Wai, 38, were charged with unlawfully assisting the Hong Kong intelligence service and engaging in foreign interference by forcing entry into a British address. The three spoke only to confirm their names, ages and addresses at an initial hearing at Westminster magistrates court. They were not asked for a plea. They were due to appear at the Old Bailey on Friday. Thames Valley police detectives are investigating whether anyone else was involved in the death, and the official designation of “unexplained” means they are yet to find anything suspicious or pointing to homicide. During the earlier hearing, the court was told that while in custody Trickett had attempted to take his own life and made threats to his own life. Kashif Malik, prosecuting, informed the judge Louisa Ciecióra: “He told two separate custody sergeants when he is released he is going to kill himself because ‘he has nothing to live for’. How realistic that is, judge, we don’t know, but that is a concern for us.” The judge granted bail. Trickett’s solicitor, Julian Hayes, said: “We are naturally shocked at this news and supporting his family as best we can. The death is currently being treated as unexplained by the police and further investigations are still ongoing. “Following a mandatory referral to the Independent Office for Police Conduct, due to the prior contact with police, the matter has now been passed on to Thames Valley police’s professional standards department. It would therefore not be appropriate for us or the family to comment any further at this stage.” Trickett’s family said: “We are mourning the loss of a much-loved son, brother and family member. We would be grateful if the press would respect our privacy at this difficult time and refrain from intruding on our grief.” Trickett, Yuen and Wai were charged with engaging in unlawful information gathering, surveillance and acts of deception between 20 December 2023 and 2 May 2024, contrary to section 3 (1) and (9) of the National Security Act 2023. They were also accused of forcing entry into a UK residential address on 1 May this year, being reckless as to whether the prohibited conduct, or course of conduct of which it forms part, would have an interference effect, contrary to section 13 (2) and (7) of the act. Yuen, of Dalston, east London, works as an office manager at Hong Kong’s Economic and Trade Office, an organisation responsible for trade and investment on behalf of the former British colony that is now a semi-autonomous region of China. Wai, a dual Chinese and British national from Staines, Surrey, works in Border Force at Heathrow. He is also a City of London special constable and the founder of a private security firm. The men were required to report weekly to a local police station, were subject to a 10pm-5am curfew and were banned from travelling abroad. They were also told to hand over their passports, register internet-connected devices with police, not use any internet concealing tools such as a VPN, and were told to sleep at their designated home addresses. The three defendants were originally detained as part of a larger operation in which 11 people were arrested earlier this month. Nine men and a woman were arrested by officers in Yorkshire and one man was arrested in London, the Met said. The seven men and one woman who were not charged were released from custody. Thames Valley police are asking anyone with information to come forward, particularly anyone who was in Grenfell Park on Sunday afternoon prior to 5.15pm.