The stepfather of an Irish girl missing in Spain for over five years has been arrested by police in Dublin on suspicion of murdering her brother.

Amy Fitzpatrick’s stepdad Dave Mahon was arrested on Sunday after her brother Dean was stabbed to death outside a northside apartment.

Mum Audrey is being comforted by family and friends after 23-year-old Dean Fitzpatrick suffered a stab wound to the abdomen in the horror attack.

His body was discovered outside stepfather Mahon’s apartment complex.

The Irish Sun reports that Audrey is struggling to cope with the latest tragedy, five years after her teenage daughter disappeared in Spain.

She told the paper: “I can’t believe it. First Amy, now this. I still don’t know what happened. I’m totally out of the loop. Dean’s girlfriend rang me, that’s how I found out.

“She thought I knew but I didn’t. I haven’t a clue what happened. I’ve spoken to the gardai (police) but nobody is really telling me anything.

“I was minding my dad, staying the night with him in his house so I wasn’t there.”

Police were called to the apartment late on Saturday night when a witness discovered Dean’s body outside.

The tragedy occurred hours after the family had celebrated younger brother Alex’s communion with his dad Christopher Fitzpatrick.

He told the paper: “Dean was a loving son, the best a father could ask for. I can’t bear the thought of not seeing him again.”

Dean’s aunt Christine Kenny told the Irish Sun: “We’re just devastated. There’s no explanation, no words we can give to this. Christopher is in complete bits.

“After all we’ve been through, this is just devastating. The family have been through hell. Christopher is our priority at the minute.”

The report says Dean was distraught when his only sister Amy went missing in Spain on New Year’s Day in 2008.

The 15-year-old was last seen walking home from a pal’s house on the Costa Del Sol.

She had been living in Spain with Audrey, stepdad Dave and brother Dean at the time.