Question: Who is the former Sri Lankan- hedge fund manager that was investigated by BJ Kang for insider trading?

Context paragraphs:
Karunasena Kodituwakku: Karunasena Kodituwakku (born March 21, 1945) is a Sri Lankan politician, academic and diplomat.  He is the current Sri Lankan Ambassador to China and former Sri Lankan Cabinet Minister of Education, Human Resources Development and Cultural Affairs and the 3rd Governor of the North Western Province of Sri Lanka.  He also served as the Vice Chancellor of University of Sri Jayewardenepura and Sri Lankan Ambassador to Japan and Republic of Korea.

John D. Arnold: John Douglas Arnold (born 1974) is an American billionaire and former hedge fund manager who specializes in natural gas trading.  His firm, Centaurus Advisors, LLC, was a Houston-based hedge fund that specialized in trading energy products.  Arnold announced his retirement from running the hedge fund on May 2, 2012.

Arvind Raghunathan: Arvind Raghunathan (born October 24, 1963) is a Hedge Fund Manager.  He is the founder and CEO of Roc Capital Management LP (the largest Hedge Fund launch of 2009).  On February 25, 2009, it was announced that Raghunathan and his associates would be leaving Deutsche Bank to set up the independent quant trading hedge fund.  It was rumored in late July 2013 that the main fund of Roc Capital Management would be liquidated after losses.

Mathew Martoma: Mathew Martoma (born May 18, 1974 as Ajai Mathew Mariamdani Thomas) is an American former hedge fund trader.  As a former portfolio manager at S.A.C. Capital Advisors, a Stamford, Connecticut-based hedge fund, he was accused of generating possibly the largest single insider trading transaction profit in history at a value of $276 million.  On November 20, 2014, he began serving a nine-year prison sentence.

Prasad Kariyawasam: Prasad Kariyawasam is a Sri Lankan diplomat and the current Secretary to the Ministry of Foreign Affairs, Sri Lanka.  He was the former Sri Lankan Ambassador to the United States.  He has also served as Sri Lankan Ambassador to India, Afghanistan and Bhutan

BJ Kang: BJ Kang is an American Federal Bureau of Investigation special agent known for high-profile investigations of securities fraud.  After leading the perp walk of Bernie Madoff in 2008 and Raj Rajaratnam in 2009, Reuters described him as possibly "the most feared man on Wall Street."

Marvan Atapattu: Deshabandu Marvan Samson Atapattu (born 22 November 1970 in Kalutara) is a former Sri Lankan cricketer and former Sri Lankan captain, who played Tests and ODIs for seventeen years for Sri Lanka.  One of the most stylish openers in world cricket, Atapattu started his career with 6 consecutive ducks in tests, but went on to become one of Sri Lanka's most prolific run scorers of all time, which included 6 double centuries in tests.

Sri Lankan Creole Malay: Sri Lankan Creole Malay (also known as "Sri Lankan Malay" and "Bahasa Melayu") is an Austronesian creole language formed through a mixture of Sinhala and Tamil with Malay.  Sri Lankan Malay is a restructured vernacular of Malay base spoken by at least five different communities in Sri Lanka which has evolved to be significantly divergent from other varieties of Malay due to intimate contact with the dominant languages of Sinhala and Tamil.  Sri Lankan Creole Malay originated as a means of communication between the incoming Malays and the Sri Lankan people in the 13th century.  It is now exclusively spoken by Sri Lankan Malays, whose ancestry include exiles and labourers brought by the Dutch and British, as well as soldiers in the Dutch garrison.  They now constitute 0.3% of the Sri Lankan population, some 46,000.

Raj Rajaratnam: Raj Rajaratnam (Tamil: ராஜ் ராஜரத்தினம் ; born Rajakumaran Rajaratnam; June 15, 1957) is a Sri Lankan-American former hedge fund manager and billionaire founder of the Galleon Group, a New York-based hedge fund management firm.  On October 16, 2009, he was arrested by the FBI for insider trading, which also caused the Galleon Group to fold.  He stood trial in "U.S. v Rajaratnam" (09 Cr.  01184) in the United States District Court for the Southern District of New York, and on May 11, 2011 was found guilty on all 14 counts of conspiracy and securities fraud.  On October 13, 2011, Rajaratnam was sentenced to 11 years in prison and fined a criminal and civil penalty of over $150 million combined.

Sri Lankan Australians: Sri Lankan Australians refers to people of Sri Lankan heritage living in Australia; this includes Sri Lankans by birth and by ancestry.  Sri Lankan Australians constitute one of the largest groups of Overseas Sri Lankans and is the largest Sri Lankan diaspora community in Oceania.  Sri Lankan Australians include Sinhalese people, Sri Lankan Tamils, Sri Lankan Moors, Burghers and others.

Supporting paragraphs: BJ Kang Raj Rajaratnam
Answer: Raj Rajaratnam