Warning: This story contains details that some may find disturbing.
A former Royal Marine found dead after he was charged with assisting the Hong Kong intelligence service told police he would harm himself after he left custody, an inquest heard.
Matthew Trickett, 37, a Home Office immigration officer, had appeared in court charged under the National Security Act and was found dead in a park in Maidenhead on 19 May 2024.
He had been arrested on 1 May 2024 and was seen to attempt self-harm in his cell on 11 May. He was put under constant supervision but released on bail two days later.
Two co-defendants charged as part of the same investigation were jailed in June.
Contractor Serco was due to fit an electronic tag to Trickett to ensure he was adhering to bail conditions imposed on him by Westminster Magistrates' Court.
But on 19 May, it told Thames Valley Police that it "had not been able to monitor" Trickett and officers sought to arrest him, Reading Coroner's Court heard.
He was later found dead in Grenfell Park by a member of the public.
The inquest into his death is expected to last until 18 November.
Custody sergeant Del May, from the Metropolitan Police, said officers had seen Trickett attempting self-harm.
May said Trickett later told him that he had a "lot of respect for police" and would not harm himself in custody, but would do so after he left.
The officer said he thought the potential harm was a "really good reason" for keeping Trickett in custody.
But doctors who monitored Trickett said his mood dipped and then improved before he was granted bail.
They attributed that change him being given testosterone, which he had been receiving before he was arrested.
Trickett's family said in a statement that he was "proud of his career" and was "well loved" by former colleagues.
'Shadow policing operation'
Originally from Wimborne, Dorset, he joined the Royal Marines aged 20 and served in the Arctic, the Mediterranean, Brunei and Afghanistan.
He had worked in security from 2013 and his clients had included Middle Eastern royal families.
His family said that while he could be "slightly naive", he made friends easily and would "put himself in harm's way without a second's thought".
Chi Leung "Peter" Wai, 40, was sentenced to 10 years and Chung Biu "Bill" Yuen, 65, was given an eight-year prison term in June.
The Chinese-British nationals were found to have been involved in a "shadow policing operation… conducted on behalf of the Hong Kong authorities, and by extension, the Chinese state".
Wai was found to have drawn Trickett into his surveillance of Hong Kong dissidents.
Among that activity, in 2023 Trickett was tasked by Wai to arrange for high-profile Hong Kong activist Nathan Law to be followed while he spoke at the Oxford Union student society.
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