Police in Thessaloniki, northern Greece, arrested a fourth suspect on Thursday in connection with an arson attack on the house of New Democracy politician Afroditi Nestora that resulted in the death of her mother, Vagia Nestora, earlier this month.

Investigators believe the latest suspect, aged 25, played a role in helping the alleged perpetrators of the attack hide before and after the July 1 firebombing of the Nestora family’s apartment building.

He is thought to have helped get the keys to an empty apartment nearby to the suspected perpetrators, a man aged 29 and a woman, 26. The apartment’s 24-year-old owner has also been arrested.

The fourth suspect’s name reportedly came up during the questioning of the 24-year-old, who denied all knowledge of his apartment having been used by the suspected perpetrators.

Investigations are continuing into the incident, which also resulted in the injury of Afroditi Nestora, her father and two other residents of the building. Vagia Nestora, 72, died several hours after the attack, having suffered burns over 80% of her body and damage to her lungs.