The four are among seven people who were formally charged in a Malaysian court after the navy arrested them during a gun battle on board a hijacked chemical tanker Jan. 20.
The other three suspected pirates, aged around 15 years, won't face death sentences because of their age, Malaysian prosecutors said.
The navy took them to face prosecution in Malaysia. The navies of India and South Korea also recently took captured pirate suspects to their own countries for trial.
Last month, in separate incidents, the navies of South Korea and Malaysia boarded pirated ships and took control of the vessels after gun battles with the pirates.
In the Malaysian operation, the tanker Bunga Laurel was in the Gulf of Aden and bound for Singapore with a cargo of lubricating oil worth more than $10 million.
The Malaysian navy answered a distress call from the Malaysian-flagged vessel and arrived in time to do battle with armed pirates who had just boarded the vessel.
The crew of 23 was freed without harm but three of the seven suspected pirates were wounded.
However, during the South Korean operation, eight of the 13 suspected pirates on board a tanker were killed and the others taken prisoner. The ship's crew of 21 was safe but the captain was shot in the stomach by a pirate and was reported in stable condition.
The International Maritime Bureau welcomed the successful rescue operations but cautioned against navies engaging in armed assault of pirated ships.
"The IMB commends the robust actions of the South Korean navy and renews its call for greater naval action in the fight against this brand of maritime crime," IMB Director Pottengal Mukundan said.
"We recognize the risks posed to crew in actions of this type and advise that navies only give the orders after consultation with a vessel's owners and flag state."
In Mumbai, 28 suspected Somali pirates captured Sunday in the Indian Ocean were handed to police and will appear in court.
They were captured near the Lakshadweep Islands, off the coast of Kerala state, by an Indian coast guard vessel that had been tracking the Thai trawler Prantalay-11.
The coast guard attacked the ship, which had been hijacked in April, captured the armed pirates and freed the vessel's 24 fishermen. The pirates had demanded $9 million in ransom for the release of the fishermen and had been using the ship as a base for attacking other vessels.
The head the Indian coast guard, Inspector General S.P.S. Basra, warned that attacks by pirates off the Indian coast are increasingly violent.
"In the recent times, Somali pirates have mounted attacks within 250 to 300 nautical miles off the coast of India. The level of force used by pirates over that period has shown an exponential increase, as well as it is more brutal and lethal," he said.
Despite the efforts of the International Maritime Bureau, whose Piracy Reporting Center has headquarters in Kuala Lumpur, the organization is concerned about the increase in attacks and hostage taking.
Last year there were 445 recorded pirate attacks, a 10 percent increase on 2009. Pirates took 1,181 hostages, the highest number since the IMB began started monitoring the area around the Gulf of Aden in 1991.
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