Murdered school teacher Aishling Murphy
The 23-year-old primary school teacher was attacked while out exercising beside a canal in Tullamore, County Offaly, last Wednesday.
The man is being questioned in relation to potential withholding of information.
Another man in his 30s remains in custody being questioned on suspicion of murdering Aishling while she was out jogging.
Aishling was laid to rest on Tuesday following Requiem Mass in her home town.
Tags: