One of the two men accused of the gruesome murder of a tailor in Udaipur has links with the Pakistan-based religious organisation Dawat-e-Islami and visited Karachi in 2014, Rajasthan police chief M.L. Lather said on Wednesday.

The police have detained three people apart from the two prime accused, Riaz Akhtari and Ghouse Mohammed, who were arrested on Tuesday hours after the murder.

“Ghouse Mohammed has links with the Karachi-based Islamist organisation Dawat-e-Islami. He visited Karachi in 2014. So far, we have detained five people, including the two prime accused,” Lather told a news conference.

A video posted online shows Kanhaiya Lal being killed with a cleaver by a man who has entered his shop posing as a customer. Later in the video, two men say they are avenging an insult to Islam and allude indirectly to suspended BJP spokesperson Nupur Sharma’s remark on Prophet Mohammed.

One of the men says they have “beheaded” the victim and goes on to threaten Prime Minister Narendra Modi, saying their knife would get him as well.

Lal had expressed support on social media for Sharma. He was arrested on June 10 over a social media post and released on bail on June 15. He later told the police he had received threat calls.

Several Muslim organisations have condemned the killing, saying it went against Islam.

“The brutal murder in Udaipur has shaken humanity. It is not only an act of cowardice but also non-Islamic, illegal and inhuman. On behalf of all Indian Muslims, I strongly condemn this,” Syed Ahmed Bukhari, the Shahi Imam of the Jama Masjid, said on Wednesday.

The Jamiat Ulema-i-Hind too said the murder went against Islam.

Rajasthan chief minister Ashok Gehlot said the killing was meant to spread terror, and added that he had received information that the killers had overseas links.

Sources said the two prime accused had watched several Islamic State videos before the murder.

The duo have been booked under the stringent Unlawful Activities (Prevention) Act. The Union home ministry on Wednesday formally directed the National Investigation Agency to take over the probe. It will be assisted by a special investigation team that the Rajasthan police had formed on Tuesday.

Curfew has been clamped in seven police station areas of Udaipur. Mobile Internet services have been suspended across all 33 districts of Rajasthan.

“We are taking the incident very seriously. This is not an ordinary issue and cannot happen until there is a link with radical elements at the national and international levels,” Gehlot told reporters on Wednesday in Jodhpur.

He later left for Jaipur to chair a law-and-order review meeting.

Gehlot had on Tuesday said there was communal tension in the country and urged Modi to address the people. He said both Hindus and Muslims were worried.

“It is more impactful if the Prime Minister speaks. I believe that the Prime Minister should address the country on this occasion and make an appeal that we will not tolerate violence at any cost. What is the problem in saying so?” he had said.