The authorities were on Thursday in the process of issuing a European Arrest Warrant for a man convicted of importing explosives, after he went missing with his wife and is believed to be in Serbia.

Sources close to the police said investigators believe Jomic Calleja Maatouk and Marzia Maatouk probably fled Malta by sea.

They said there had been no alerts for Calleja Maatouk at the airport or seaport. This led them to believe they either used false passports to get out of the country or crossed to Sicily by sea and then drove through Italy.

Sources on Thursday said the authorities were going to issue arrest warrants for the couple and their information was that they were probably in Serbia, which has an extradition agreement with Malta.

Calleja Maatouk, 36, was sentenced to five years in jail after he was convicted of importing explosives and trying to buy poison. He must also serve a prison sentence over drug offences.

He was out on bail after he appealed his conviction but did not sign a bail book for a number of days.

In court, Magistrate Donatella Frendo Dimech had described him as a “lethal weapon” who was ready to open “the gates of hell upon whoever he deemed an inconvenience to be eliminated”.

Calleja Maatouk had been caught trying to import deadly material that included lethal doses of radioactive material Polonium-210, highly toxic poison Ricin, killer drug Fentanyl and C-4 explosives.

His wife, 23-year-old Marzia, was last month sentenced to 15 months in jail after she was convicted of cannabis possession with intent. The crime took place in August 2019 when she was just 19 years old.

She was caught with 340 grams of cannabis as well as other drug paraphernalia outside McDonald’s in Birkirkara in a car with Jomic Calleja, who was her boyfriend at the time.

Maatouk’s family have told Times of Malta they are fearing for her safety after the couple’s home was found in disarray.

Speaking on condition of anonymity, the family said Marzia has not been online on WhatsApp since Wednesday and calls to her mobile phone were returning voicemail messages that appeared to indicate it has been switched off for days.

Her brother was the first to sound the alarm last Thursday, when his sister did not show up at his shop to cover a shift and was not taking his calls.

Her grandmother also began to suspect something was wrong when she tried calling her several times and could not reach her. The distressed woman filed a police report last Friday.

“We are extremely worried she might have been forced to leave the country and that she might be in danger right now,” one tearful relative said.

They said that when police and civil protection officers searched the couple’s house on Saturday, it looked as if someone had left “in a rush”. “And it is not typical of Marzia and her husband. They are usually very organised people.”

Police and civil protection officials also found eight dogs and a bird inside the house ­– all pets of the couple. By Monday evening they had been relocated to other homes or animal shelters.

Calleja Maatouk has a long criminal record as well as a history of fleeing the law. In 2015 he was arrested aboard a train in Sicily heading to the Italian mainland, having left Malta as he faced criminal proceedings related to cannabis trafficking.