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
Barry Bennell, the former football coach who has been convicted of 43 counts of historical child sex offences, will be sentenced today.
A police officer from Bury has been nicknamed "The Hoff" after he jumped into a freezing, fast-flowing river to save a man in distress.
Mild, drizzly start to the new week - then 'all change'