Police in Lancashire are hunting a man from Chorley who posted "sick" comments about missing schoolgirl April Jones online.
His comments sparked an angry backlash on Facebook.
A vigilante group is reported to have called at the man's parents' house in Chorley.
Lancashire Police confirmed it was investigating the comments and was looking for a man in connection with their inquiry.
More top news
Ex-Coronation Street star Bruno Langley has said the sexual assaults he carried out were "dreadful" but insisted he is not a danger.
A man and woman have died in a car crash which also left two children seriously injured.
Wayne Rooney has said his community service in a garden centre after admitting drink driving is "refreshing" and "relaxing".