The pathologist who first examined the body of Ian Tomlinson has said being struck and pushed over by police may have caused a heart attack.
Dr Freddy Patel concluded that the paper seller died from a heart attack at the G20 protests in April 2009.
However, he told the inquest on Mr Tomlinson that he could not establish a "causal link" between the police incident and his death.
The jury also heard Mr Tomlinson was five times over the drink-drive limit.
Under cross-examination, Dr Patel said that a baton strike and a heavy fall could cause stress and that it was "well known" that a stressful situation could be a significant contribution to a heart attack.
He told the inquest there was a "compelling association" between Mr Tomlinson being pushed over by an officer and his collapse shortly after.
But he could not establish that the incident was the actual cause of death.
The inquest also heard that Dr Patel was suspended by the General Medical Council for failings in his post-mortem examinations in other cases for three months in 2010 and is currently serving a further four-month suspension.
The jury had already heard that two pathologists disagreed with Dr Patel's finding that death was due to natural causes and believed that Mr Tomlinson died from internal bleeding. And they were told - for the first time - that a third pathologist had come to the same conclusion.
The inquest at the International Dispute Resolution Centre has heard the 47-year-old fell to the ground after Pc Simon Harwood hit him on the thigh with a baton and then shoved him from behind.
Mr Tomlinson, who was not part of the G20 protest, got back to his feet but collapsed and died minutes later.
Under cross-examination by counsel to the inquest Alison Hewitt, Dr Patel agreed his post mortem examination report finding stated: "Death was a result of acute coronary syndrome and is well-recognised that it can cause sudden and unexpected death at any moment, spontaneously or precipitated by a stressful situation or physical exertion, depending on the temporal circumstances."
He was also questioned by Matthew Ryder QC, barrister for Mr Tomlinson's family, about whether the shove could have been a "significant contribution" to a heart attack
Dr Patel said: "What I'm saying is that there is a compelling association, but there is no causal evidence. A pathologist cannot say that caused it without the evidence."
His post-mortem examination report acknowledged that a large "tramline" bruise on Mr Tomlinson's left leg could have been caused by Pc Harwood but at the inquest he maintained the evidence did not support the theory he suffered massive internal bleeding.
At an earlier hearing, some witnesses said Mr Tomlinson that he had appeared drunk as he walked home through the G20 protest, although his work colleague denied this was the case.
The results of the toxicology tests conducted on samples of blood taken from Mr Tomlinson's body at the post-mortem examination were disclosed during Dr Patel's evidence to the inquest.
Dr Patel said the tests found Mr Tomlinson had 400 milligrams of alcohol per 100 millilitres of blood, the legal limit for driving being 80.
He also admitted changing the wording of his post-mortem examination report exactly a year later.
But Dr Patel said he did so because "the issue arose on the cause of death and it appeared to me that other experts have misinterpreted what I was trying to convey in my report".
The pathologist amended the wording over references to fluids in Mr Tomlinson's abdomen, which he decided was a mixture of blood and a liquid called ascites produced by liver disease.
The jury was told the abdominal fluid was thrown away before the other pathologists disputed Dr Patel's findings.
Questioned about his changes, Dr Patel told the London inquest: "I was trying to make it quite clear that it wasn't pure blood. It was ascites fluid with some blood in it."
He wrote in his first report: "Intra-abdominal fluid blood about 3 litres, small blood clot."
Exactly a year later, he revised it to: "Intra-abdominal fluid with blood about 3 litres and small blood clot."
The hearing continues.