Malaysian authorities have refocused investigation on the crew and passengers of the missing Malaysia Airlines jet after the plane was thought to be diverted deliberately.

Three plain-clothes police officers on Saturday afternoon searched the home of Zaharie Ahmad Shah, the 53-year-old captain of the vanished Flight MH370, Malaysia's state news agency Bernama reported.

The veteran pilot, who joined Malaysia Airlines in 1981 and was promoted to captain in the 1990s, has more than 18,000 hours of flying experiences. The search of his home took about an hour and a half.

The experienced captain was keen on cooking and had great enthusiasm for flying. Colleagues and friends do not believe that he would have hijacked the plane.

The home of the 27-year-old co-pilot was also searched. Fariq Ab Hamid joined Malaysia Airlines in 2007 and has accumulated 2,763 hours of flying experiences. Family and friends say he was religious and serious about his career, countering speculation that he might have deliberately steered the plane off course.

Police said an official statement on the search will be released at a news conference Sunday.

"I cannot make any statement when investigation is still going on," said a police spokesman.

According to the Malay Mail newspaper, the family of the captain had moved out of their residence in Laman Seri before the flight's disappearance nine days ago.

At the request of the Malaysian authorities, India on Saturday joined search and rescue for the Boeing 777 with 239 people on board.

The search mission is now shifted to the southern Indian Ocean as evidence showed that military radar caught traces of the plane over the Straits of Malacca in the west after it lost contact with air controllers en route to Beijing in the northeast.

A U.S. official reportedly said faint electric signals sent to satellites from the missing jet showed it may have been flown thousands of miles off course before running out of fuel over the Indian Ocean.

However, an unnamed Indian officer said it was unlikely that the plane had flown above Indian airspace as it could have come under attack.

"We are surprised that the Malaysian military authorities did not react for two days after their primary radar spotted the plane," he was quoted as saying.

"Surveillance authorities should immediately react to anonymous flights and such information should be shared across civilian and military agencies too. If the assumptions are true, the missing plane would have needed to fly through the airspace of several countries in the region," the officer said.

With the search and rescue mission stretching into the ninth day, China urged Malaysia to continue providing "thorough and accurate information."

"The Chinese government and all the people in the country pay great attention to the latest news on the missing Malaysia Airlines jet," Chinese Deputy Foreign Minister Xie Hangsheng told Iskandar Sarudin, Malaysian ambassador to China, Saturday afternoon. The plane was carrying 154 Chinese.

A multinational hunt for the missing passenger jet, carried out mainly in the South China Sea, has been futile.