Mrs Duplain said that she then returned home and picked up her husband and returned to the motorway, finding him waving his jacket at passing cars.She said that he did not recognise them but they persuaded him to get into the car where he lay on the back seat kicking at the windows forcing her to stop the vehicle again.Mr Kaiser got out of the car and ran across the motorway and was struck by a Volkswagen Polo being driven on the northbound carriageway. He died from severe head injuries at the scene.Mrs Duplain said: “I said to Andy ‘He’s going to get killed’ and then I heard him being hit by the car.”Mrs Duplain said that she later found out from Mr Kaiser’s family that he had been diagnosed with a brain tumour, was signed off sick but had carried on working. I said to Andy ‘He’s going to get killed’ and then I heard him being hit by the carSue Duplain Her husband, Andrew, said they had called the NHS number 111 but had not been given any advice on what to do.He said: “They really couldn’t do much. The way he was talking it was clear he wasn’t in control, he couldn’t be trusted, he needed to be locked up to be fair.”Later that evening, as Mrs Duplain was driving work colleague Mr Kaiser to the hotel where he was staying, he grabbed the steering wheel forcing her to stop on the hard shoulder of the A3(M) near Clanfield where he jumped out of the car.She told the Portsmouth inquest: “There was no warning whatsoever. He had got his phone, his passport, keys, wallet and everything and was stuffing everything between my knees. I screamed at him and swore at him and said ‘Are you trying to kill the both of us?’.” Recording a verdict of accidental death, coroner David Horsley said to Mrs Duplain and her husband: “It seems he did have some underlying problem with his brain which had recently caused his behaviour to become extremely erratic.”He was a highly stressed and nervous person but his behaviour that day and night was beyond anything you could have contemplated.”It must have been a dreadful experience for you both. It was a nightmare situation. His behaviour was totally irrational and I think we have an explanation why it was irrational.”He did not know what he was doing and things were further complicated by the fact he was German and they drive on the other side of the road. I do not think he was aware a car was coming at him.” It was a nightmare situation. His behaviour was totally irrational and I think we have an explanation why it was irrationalDavid Horsley, coroner A German man who came to the UK to visit friends ran was killed when he ran across a motorway after a brain tumour he was suffering from caused him to behave “erratically and out of control”, an inquest has heard.Alexander Kaiser, from the Westerwald region of Germany, had flown to the UK on June 5 after suffering stress in his relationship with his partner of 10 years.But after friend Sue Duplain had picked the 35-year-old up from Heathrow airport he began to behave “bizarrely” including repeatedly asking her to give him high-fives, trying to escape from the garden of their home in Horndean, Hampshire, and asking for a beer before throwing it away. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.