(CNN) The man accused of killing 51 worshipers at two Christchurch mosques has been charged by New Zealand police with engaging in a "terrorist act," the first time such a charge has been laid inside the country.

Australian citizen Brenton Tarrant, 28, faces an additional 51 charges of murder and 40 of attempted murder for the March attack which was New Zealand's worst mass shooting in modern history, New Zealand police said in a statement Tuesday

A Turkish citizen died in hospital earlier this month, bringing the total death toll to 51.

Tarrant, who allegedly wrote an anti-immigrant, anti-Muslim manifesto , also faces one charge under the Terrorism Suppression Act 2002, the first time anyone has been prosecuted under the act, a police spokesperson confirmed to CNN.

The charge of committing a terrorist act carries a possible life sentence.

Andrew Geddis, a law professor at New Zealand's Otago University, said that if Tarrant was convicted, the additional terrorism charge wouldn't result in a heavier punishment. Instead, the charge was about labeling the alleged shooter's action as terrorism.

"It's using the legal process to send a message," he said.

Following the shooting on March 15, New Zealand Prime Minister Jacinda Ardern said : "It is clear that this can only be described as a terrorist attack."

New Zealand's terrorism law was introduced in 2002 in the wake of the 9/11 attacks.

Police referred to the Act in search warrants for 2007 raids in the Te Urewera ranges, a rugged, sparsely populated area of the North Island where police believed Maori terrorists were running military-style training camps as part of a plot to bomb Parliament.

Ultimately none of the people arrested in the raid faced charges under the act as the Solicitor-General found the evidence was insufficient.