India has executed the only death row convict in the country's deadliest terror attack, the 1993 Bombay bombings, which killed a total of 257 people.

Yakub Abdul Razak Memon was hanged early Thursday after Indian President Pranab Mukerjee rejected a last-minute mercy plea, state TV stations reported.

Memon, 53, was executed inside a prison in western India, where he had been incarcerated since 1994.

An accountant by profession, he was convicted in 2007 of helping raise funds for the serial blasts that rocked Mumbai, the financial capital of India, over two decades ago. The city was known as Bombay until 1995, when its name was officially changed to Mumbai.

By late Wednesday, authorities said, Memon exhausted all the legal possibilities to escape the death penalty.

His lawyers had argued that an execution can only be carried out after seven days have passed since the rejection of a mercy petition.

Prominent citizens, including retired Supreme Court judges, had urged Indian President Mukerjee to commute Memon’s sentence to life in prison.

The convict’s brother, Tiger Memon, is widely seen as having been the mastermind of the attacks, alongside another suspect Dawood Ibrahim. Both remain in hiding.

The Bombay Stock Exchange, the offices of national carrier Air India, and a luxury hotel were among about a dozen targets of the March 1993 blasts. Bombs were packed into cars and scooters and were planted in a manhole and a hotel room, and were detonated over a span of two hours in the afternoon on March 12, 1993.

The explosions were seen as retaliation for the demolition of a 16th-century mosque in northern India by Hindu nationalists. The mosque’s demolition sparked religious protests in many parts of the country, leaving more than 800 people dead, most of them Muslims.

The 1993 attacks were followed by the lengthiest trials in India’s history, with 686 witnesses giving testimonies, which filled 13,000 pages.

A total of 100 people were convicted of involvement in the blasts. The accused included gangsters, housewives and a Bollywood movie star. Ten of those were also sentenced to death, but had their sentences commuted to life in prison. Memon, however, had his sentence unchanged.