The 800-year-old heart of Dublin’s patron saint has been recovered by police, six years after it was stolen from a cathedral in the city.

The relic – the heart of St Laurence O’Toole – was taken from Christ Church Cathedral in 2012. It has no monetary value but is “a priceless treasure” for the church, said the cathedral’s dean, the Very Rev Dermot Dunne.

The theft of the relic, which had been kept in a wooden heart-shaped box within a small iron-barred cage, sparked a six-year investigation by gardaí.

The relic was presented to the archbishop of Dublin, Michael Jackson, on Thursday evening by garda assistant commissioner Pat Leahy.

A choir sang to mark the heart’s return, with churchgoers queuing up to catch a glimpse and give prayers of thanks. Jackson thanked those who had helped recover the item and described its return as a joyful moment for the people of the city.

Its return “brings great joy to the people of Dublin as Dubliners,” he said.

“For those of us associated with the life of the dioceses, it brings again to the fore the close relationship between Glendalough and Dublin, a relationship of more than 800 years. Laurence left the monastic city of Glendalough of which he was abbot to become archbishop of Dublin, hence cementing a vibrant relationship that continues unabated to this day.”

Leahy commended officers who had “kept their radars on and their minds open in this ongoing investigation”. No arrests have been made, gardaí said.

The church said there would now be a shrine in the cathedral to St Laurence, who died in 1180.