A top Bangladeshi politician accused of masterminding a deadly 2004 grenade attack against ex-premier Sheikh Hasina had his conviction quashed Sunday, another step in his expected return from London exile.

Tarique Rahman, the son of two-time premier Khaleda Zia and de facto leader of the Bangladesh Nationalist Party (BNP) was convicted in absentia for the attack on a political rally called by Hasina.

But the High Court in Dhaka ruled that the guilty verdict against him and 48 others was illegal as the trial court did not properly follow procedure.

The BNP has consistently denied involvement in the attack and accused Hasina’s government of political interference in the trial to persecute her opponents.

“The state presented 225 witnesses, none of whom testified to seeing any of the accused hurl grenades or participate in conspiracy meetings,” lead defence lawyer S.M. Shahjahan told reporters after Sunday’s verdict.

The 2004 grenade attack targeted a rally by Hasina’s Awami League party, which was in opposition at the time, and the blast occurred just as Hasina was finishing her speech.

Tarique’s mother Zia, Hasina’s longtime rival and premier at the time, ran a government accused of interfering with the original investigation into the attack, which killed more than two dozen people.

Shishir Monir, another defence lawyer, said that a later probe under Hasina had forced suspects into naming Tarique and other BNP leaders as culprits in the attack.

“The Task Force for Intelligence detained the accused for up to 261 days and forcibly extracted their confessions,” he told reporters.

“While we empathise with the victims of the grenade attack who deserve justice … the government should have sought out the real perpetrators,” he added.

Hasina fled the country in August after a student-led revolution brought down the curtain on her autocratic tenure of 15 years.

With his mother in ailing health, Tarique is widely expected to eventually return to Bangladesh after more than 15 years living in exile in London and lead the BNP in her stead.

Rafiqul Islam, a key witness in the grenade case that led to the 2018 convictions, said that the families of those killed and injured were still in need of justice despite Sunday’s verdict.

“I saw… body parts strewn on the street,” he told AFP.“The court has acquitted everyone,” he added. “But the victims still deserve justice. “