A 17-year-old was arrested on Tuesday morning after malicious tweets were sent to Olympic diver Tom Daley.
Dorset Police said the teenager was held at a guesthouse in Weymouth hours after 18-year-old Daley received the messages on social networking site Twitter.
A police spokeswoman said: "A 17-year-old man was arrested by Dorset Police officers in the early hours this morning at a guesthouse in the Weymouth area on suspicion of malicious communications. He is currently helping police with their inquiries."
Daley and his Team GB diving partner Pete Waterfield missed out on a medal on Monday when they finished fourth in the men's synchronised 10m platform diving event at the Olympics.
Shortly afterwards, Daley retweeted a message from user Rileyy_69 which said: "You let your dad down i hope you know that." Daley responded by tweeting: "After giving it my all... you get idiots sending me this..."
Daley's father Rob died last year from brain cancer. Speaking before the Olympics, Daley revealed that his father "gave me all the inspiration that I've needed".
The teenager, from Plymouth in Devon, told the BBC: "Winning a medal would make all the struggles that I've had worthwhile. It's been my dream since a very young age to compete at an Olympics. I'm doing it for myself and my dad. It was both our dreams from a very young age. I always wanted to do it and Dad was so supportive of everything. It would make it extra special to do it for him."
When news of the insensitive tweet spread, Rileyy_69 attempted to apologise.
He tweeted: "@TomDaley1994 I'm sorry mate i just wanted you to win cause its the olympics I'm just annoyed we didn't win I'm sorry tom accept my apology."
He later added: "please i don't want to be hated I'm just sorry you didn't win i was rooting for you pal to do britain all proud just so upset."