Vincent Muscat changed his plea to guilty on Tuesday and was immediately sentenced at the courtroom in the capital Valletta.
Ms Caruana Galizia, an investigative journalist who specialised in probing corruption, was killed by a bomb while driving in October 2017.
Proceedings against brothers Alfred and George Degiorgio, who have maintained their not guilty pleas, will continue. A fourth man, hotelier Yorgen Fenech, is being charged separately.
As the development unfolded, police arrested three men believed to have supplied the device that killed Ms Caruana Galizia. They are set to be charged in court in the coming days.
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23 February 2021
The moon is partially seen in the sky as lava flows from the Mount Etna volcano, near Catania in Sicily
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22 February 2021
Serbia’s Novak Djokovic celebrates with the Australian Open trophy after winning his final match against Russia’s Daniil Medvedev
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21 February 2021
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20 February 2021
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19 February 2021
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18 February 2021
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17 February 2021
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16 February 2021
Princess Latifa bint Mohammed Al Maktoum, the daughter of the ruler of Dubai says she is being held “hostage” in a villa in the middle eastern country, two years after her attempted escape from the wealthy emirate was foiled by her father
Princess Latifa/BBC
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15 February 2021
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14 February 2021
Russian women holding roses and signs form a human chain using Valentine’s Day to express support for the wife of jailed opposition leader Navalny and political prisoners, in Saint Petersburg
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13 February 2021
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12 February 2021
Huge coronavirus-shaped and submarine-shaped balloons float in the Yarkon River during a protest over the governments handling of the Covid-19 crisis and Israeli Prime Minister Benjamin Netanyahu’s alleged corruption, in Tel Aviv
Reuters
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11 February 2021
Protest against the dissolution of parliament in Kathmandu
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10 February 2021
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9 February 2021
Journalists gather for the arrival of leader of the right-wing party Forza Italia, Silvio Berlusconi, at Palazzo Montecitorio, the seat of the lower house of parliament in Rome, for a meeting with ex-central banker Mario Draghi.The former president of the European Central Bank is under pressure to secure the parliamentary support he needs to be sworn in as prime minister before the end of the week
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8 February 2021
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7 February 2021
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6 February 2021
A protester shouts slogans in front of a National League for Democracy (NLD) flag during a protest against the military coup, in Yangon, Myanmar
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5 February 2021
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4 February 2021
A folk artist performs a diabolo dragon dance, a traditional Chinese performance, in front of one of the buildings at the Qingshan Ancient Town in Qingzhou, in eastern China’s Shandong province
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3 February 2021
Indian Air Force’s Advanced Light Helicopter ‘Sarang’ acrobatic team performs during the first day of the Aero India 2021 Airshow at the Yelahanka Air Force Station in Bangalore
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2 February 2021
A mound of snow is seen outside Times Square in New York on February 2, 2021. – A huge snowstorm has brought chaos to the United States’ east coast, shuttering airports, closing schools and forcing the postponement of coronavirus vaccinations into Tuesday morning as New York City steeled itself for possibly one of its heaviest ever snowfalls. New York declared a state of emergency restricting non-essential travel, moved all children back to remote learning and rescheduled long-awaited vaccine shots as some parts of the city were hit by more than 18 inches (1.5 feet) of snow. CNN meteorologists said that figure could reach two feet before the storm comes to an end.
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1 February 2021
A demonstrator holds a photo of Aung San Suu Kyi during a protest against a Myanmar military coup at the Myanmar embassy in Bangkok, Thailand
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31 January 2021
Riot police detain a man during a rally in support of jailed opposition leader Alexei Navalny in the far eastern city of Vladivostok
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30 January 2021
A farmer holds onto his walking stick as he takes part in a protest against the central government’s recent agricultural reforms at the Delhi-Uttar Pradesh state border in Ghazipur, India
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29 January 2021
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28 January 2021
Lebanese anti-government protesters burn garbage as they go around the homes of deputies and government officials in the northern port city of Tripoli to protest the economic situation and their role in leading the country to crisis
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27 January 2021
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26 January 2021
A farmer holds a sword during a protest against farm laws introduced by the government, at the historic Red Fort in Delhi, India
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25 January 2021
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24 January 2021
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23 January 2021
Law enforcement officers detain a woman during a rally in support of jailed Russian opposition leader Alexei Navalny in Moscow, Russia
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22 January 2021
People line up to get their nucleic acid test following the outbreak of coronavirus in Beijing, China
Reuters
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21 January 2021
Activists of the Nepalese Communist party and riot police scuffle during torch protest against the Prime Minister K.P. Sharma Oli in Kathmandu, Nepal. Hundreds of student activists of Nepal’s communist party staged the torch rally demonstration against the Prime Minister KP Sharma Oli government’s move of dissolving the House of Representatives
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20 January 2021
Joe Biden is sworn in as the 46th president of the United States by Chief Justice John Roberts as Jill Biden holds the Bible during the 59th Presidential Inauguration at the U.S. Capitol in Washington
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19 January 2021
People help a woman to take a bath in the icy waters of a frozen lake during the celebration of the Epiphany holiday near the the village of Leninskoe
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18 January 2021
A man works in the UNESCO-listed Lavaux vineyards overlooking Lake Leman after a snowfall on a winter day in Riex, Switzerland
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17 December 2021
A still image taken from video footage shows law enforcement officers speaking with Russian opposition leader Alexei Navalny before leading him away at Sheremetyevo airport in Moscow, Russia
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16 January 2021
Thai police arrest an anti-government protester attending a rally at the Victory Monument in Bangkok, Thailand
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15 January 2021
A man on skis crosses a street in Zurich, Switzerland
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14 January 2021
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13 January 2021
Students wearing traditional Punjabi outfits perform a folk dance to celebrate Lohri, the spring festival, in Amritsar
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12 January 2021
Georgia’s Tato Grigalashvili (white) and Netherlands’ Frank De Wit fight during the men’s under 81kg category of the World Judo Masters in the Qatari capital Doha
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11 January 2021
A car submerged on a flooded street in the town of Fushe Kosove after heavy rain and snow showers in Kosovo
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10 January 2021
Indonesian Navy personnel carry debris believed to be from the Sriwijaya Air SJ-182 plane, which crashed into the sea, off the Jakarta coast
Reuters
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9 January 2021
Two friends spend some time at a self-made terrace in Callao Street during the snowfall in Madrid, Spain. Storm Filomena brought the heaviest snowfall in decades
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8 January 2021
A woman throws hot water into the air, which instantly condenses into ice crystals amid temperatures of minus 27 degrees Celsius, in Shenyang in northeastern China’s Liaoning province
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7 January 2021
France’s biker Pasca Rauber rests at the foot of a truck during the Stage 5 of the Dakar Rally 2021 between Riyadh and Buraydah in Saudi Arabia, on January 7, 2021
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6 January 2021
Believers burn dried oak branches, which symbolise the Yule log, on Orthodox Christmas Eve in front of the Saint Sava temple in Belgrade, Serbia
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5 January 2021
A man carries bricks in a brickfield in Saver on the outskirts of Dhaka
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Ms Caruana Galizia’s killing led to international calls for accountability, as her investigative reporting had targeted the government of then-premier Joseph Muscat with claims that corruption was everywhere in political and business circles in the island nation.
Joseph Muscat, who is not related to the suspect, resigned last year in the wake of the scandal.
Additional reporting by Associated Press