The Lebanese army has detained a suspect in the murder of an Irish UN peacekeeper who was killed earlier this month after his convoy in southern Lebanon came under fire, according to sources.

The Lebanese militant Hezbollah group, which has denied any involvement in the death, has strong support in the region of the shooting attack on December 14 that took place close to the southern town of Al-Aqbiya.

Hezbollah spokeswoman Rana Sahili said on Friday that the Lebanese army arrested the suspect “in cooperation with Hezbollah,” and that he wasn’t a member of the militant group.

Two Lebanese security officials confirmed the arrest, speaking on condition of anonymity in line with regulations, and said the investigation into the killing is ongoing. They did not identify or provide any details about the suspect.

Initially, the military detained three people in connection with the attack but released two who were found not to have been involved in the killing, one of the security officials said.

Andrea Tenenti, spokesman for the UN peacekeeping mission known as UNIFIL, said the peacekeepers have yet to receive “official information” regarding any arrests.

On the fatal night, 24 year-old Pvt. Seán Rooney of Newtowncunningham and several other Irish peacekeepers were on their way from their base in the south to the Beirut airport. Two UN vehicles apparently took a detour through Al-Aqbiya, which is not part of the area under the peacekeepers’ mandate.

According to earlier reports, a group of angry residents confronted the peacekeepers, claiming they were outside their jurisdiction, and opened fire at their vehicles. Confrontations between residents in southern Lebanon and UNIFIL troops are not uncommon.

However, one of the two security officials said the suspect who was arrested had been part of a group that followed the UN convoy from the town of Sarafand, about 4 kilometers (2.5 miles) away, suggesting a targeted attack.

The conflicting reports about the attack could not be immediately reconciled.

Rooney was buried in Ireland last week, while another Irish peacekeeper, who was wounded in the attack, 22-year-old Pvt. Shane Kearney, was medically evacuated from Lebanon to Ireland.

UNIFIL was created to oversee the withdrawal of Israeli troops from southern Lebanon after a 1978 invasion. The UN expanded its mission following the 2006 war between Israel and the Iran-backed Hezbollah, allowing peacekeepers to deploy along the Israeli border to help the Lebanese military extend its authority into the country’s south for the first time in decades.

Hezbollah supporters in Lebanon frequently accuse the UN mission of collusion with Israel, while Israel has accused the peacekeepers of turning a blind eye to Hezbollah’s military activities in southern Lebanon.