A 65-year-old woman and a 25-year-old man have been arrested on suspicion of encouraging or assisting a suicide.
Sussex Police confirmed the pair were arrested in the Chichester area and it has been reported that they had planned to accompany a 71-year-old man to Switzerland to end his life.
Police are investigating to see if the man is able to decide to travel himself.
A Sussex Police spokesperson said: “The investigation is looking into what steps, if any, the suspects had made in taking the man out of the country.
“If it is confirmed the man had the mental capacity to make decisions for himself then we would not be able to prevent him travelling.”
More top news
The parents of a missing 15-year-old girl have asked their daughter to come home in a statement released alongside Avon and Somerset Police.
For an 11 year old Syrian boy named Saleh, courage comes in learning to ride his new bike again.
A misty and cloudy night should keep frost away for most of the UK, with some spells of rain overnight.