Johannesburg, South Africa - The government of Eswatini has criticized speculation it may have been responsible for the killing of well-known human rights lawyer Thulani Maseko and has pledged to investigate. Maseko, who was shot dead at his home Saturday, was an outspoken critic of the government, which rights groups say made him a target in the past.

Rights groups, Western embassies, and the U.N. have all expressed concern over the killing.

By most accounts Maseko, who was shot dead by unknown gunmen at his home over the weekend, was one of Eswatini's shining lights, a rare critical voice in Africa's last remaining absolute monarchy.

The 52-year-old, a former fellow at American University's Washington College of Law, was a human rights lawyer, prominent opposition politician and columnist.

FILE - King Mswati III of Eswatini addresses the 74th session of the United Nations General Assembly, Sept. 25, 2019.

He was a thorn in the side of the government of Eswatini, formerly known as Swaziland, and had been jailed for more than a year in 2014. Maseko's death came just hours after the king, Mswati III, spoke against activists challenging his rule.

Robert Shivambu, Amnesty International's southern Africa spokesman, called for justice for Maseko's family.

'The cold-blooded unlawful killing of Thulani Maseko offers a chilling reminder that human rights defenders, especially those at the front of calling for political reform in Eswatini, are not safe,' Shivambu said. 'If they're not being persecuted, harassed or intimidated by the state, they are at risk of losing their lives. Maseko's family deserves justice; his killers must be brought to trial.'

Shivambu said any investigation must be conducted separately from the government and its agencies.

Eswatini, a small kingdom bordering South Africa and Mozambique and a former British colony, has been ruled by the king since 1986.

He has absolute power and has regularly been accused of human rights abuses. In 2021, there were large pro-democracy protests that resulted in several deaths.

Eswatini government spokesman Alpheous Nxumalo hit back at what he said were unjust 'insinuations' on social media that the government had any hand in Maseko's killing.

'The position of government is the same, we are baffled, we are taken aback, and we are very disappointed that you are quoting political activists in the country and in South Africa who are blaming government for the murderous crime that has been committed against the person of Mr. Maseko,' Nxumalo said. 'Government has got no, absolutely no, hand in the murder of Mr. Maseko.'

He said an investigation was under way into who was responsible.

'Mr. Maseko has been doing human rights activism in this country for a long time,' Nxumalo said. 'He has been out to schools internationally, came back, continued with his agenda. He was absolutely no threat whatsoever at any given time as we were pursing our political agenda in the country.'

Amnesty's Shivambu said Maseko's death, which already has sent a chilling message to pro-democracy activists across the country, may signify an escalation in attacks against those who are openly seeking political reforms.

The story has made international headlines, with United Nations Human Rights chief Volker Türk urging an impartial investigation into the killing. The U.S. embassy in Eswatini expressed 'profound sadness' at the murder, while the European Union voiced 'grave concern' about the rights situation in Eswatini.