A man arrested in connection with the death of Dean Fitzpatrick has been released without charge.
The man, in his 40s, was being questioned about the fatal stabbing of the 23-year-old at Northern Cross in Dublin on May 25.
Investigating gardai arrested him in Coolock at around 9.30am on Friday and held him at the local Garda station under Section 4 of the Criminal Justice Act.
They will now prepare a file for the director of public prosecutions.
Mr Fitzpatrick, the older brother of Amy Fitzpatrick who went missing in Spain in 2008 aged 15, was found dead at an apartment complex after being stabbed.
A man in his 40s and known to the Fitzpatrick family was previously questioned in connection with the killing.