UK Police say a man has been arrested in relation to malicious Twitter postings directed at British Olympic diver Tom Daley.

Daley’s father died of brain cancer a year ago and the 18-year-old Olympian had hoped win a medal “for myself and my dad”. But he finished fourth on Monday, out of medal contention, in the 10-meter synchronized platform with teammate Pete Waterfield.

Afterward, a Twitter user sent him several negative messages.

Dorset Police said early Tuesday that a 17-year-old man was arrested “on suspicion of malicious communications” in relation to Twitter threats made against Daley.

Police said the man was detained at a guest house in Weymouth, and is currently helping police with their inquiries.

In Britain, tweeting messages considered menacing can lead to prosecution.