Prosecutors say Christopher Lemonius was killed after a confrontation between two groups of men.
The 32-year-old went into the water and "got into difficulty", Thames Valley Police say.
Officers from around the UK will assist during the US president's visit, the police federation warns.
The US president will stay overnight in London but will spend much of his time outside the capital.
Lewis Hamilton says he expects a "serious fight" with Ferrari at the British Grand Prix this weekend.
Ferrari's Sebastian Vettel is a surprise pace-setter ahead of Lewis Hamilton's Mercedes in second practice at the British Grand Prix.
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About 20,000 ticket holders for forthcoming events will not be reimbursed, administrators say.
Police are investigating possible physical assaults on boys in Banbury and Bristol.
Meet the people on the streets that share their names with England's World Cup stars.
Rail services will not be stopping at Oxford Station as 'noisy' and 'unsociable' works begin.
Funeral directors paid for service in Faringdon which was attended by carers and military personnel
The two authorities hoped to save money by contracting out shared services to Capita.
Oxfordshire County Council has asked parish and town councils to carry out repairs on its behalf.
Thousands of people will watch rowers battle it out at the Henley Royal Regatta over the next five days.
Police discover a 54-year-old man dead at a property in Oxford.
A new exhibition reappraises the work of Harry Burton, who photographed the decade-long Tutankhamun excavation.
A driver was airlifted to hospital and road resurfacing will take place due to a serious diesel spill.
League One side Oxford United sign Everton defender Luke Garbutt on a season long-loan deal.