Alalasundaram was from Nayanmarkaddu near Nallur in northern British Ceylon. He studied in Madras and after graduation became a teacher.
Alalasundaram was the Illankai Tamil Arasu Kachchi (Federal Party) candidate for Kilinochchi at the 1970 parliamentary election but was defeated by the All Ceylon Tamil Congress candidate. In 1972 the ITAK, ACTC and others formed the Tamil United Front (later renamed Tamil United Liberation Front). In March 1981 S. Kathiravelupillai, the TULF MP for Kopay, died and Alalasundaram was nominated by the TULF as his replacement. Alalasundaram entered Parliament after being sworn in on 23 July 1981. Alalasundaram and all other TULF MPs boycotted Parliament from the middle of 1983 for a number of reasons: they were under pressure from Sri Lankan Tamil militants not to stay in Parliament beyond their normal six-year term; the Sixth Amendment to the Constitution of Sri Lanka required them to swear an oath unconditionally renouncing support for a separate state; and the Black July riots in which up to 3,000 Tamils were murdered by Sinhalese mobs. After three months of absence, Alalasundaram forfeited his seat in Parliament on 5 January 1984. Many leading Tamil politicians fled to Madras but Alalasundaram was one of the few who remained in Sri Lanka. He stayed at his house near Nallur documenting the growing violence.
On the night of 2/3 September 1985 two men went to the house of Alalasundaram at Kalliyankadu, Nallur and kidnapped him at gun point. They took Alalasundaram in a car and drove to Uduvil where V. Dharmalingam, former MP for Manipay, was attending a wedding. The men then kidnapped Dharmalingam as well. The next day Alalasundaram’s body was found in a scrub jungle near his home at Kalliyankadu with bullet wounds in the chest and arm. Dharmalingam’s body was found at a cemetery in Thavady, Manipay, with a bullet wound in the forehead.
No one claimed responsibility for the murders. Dharmalingam’s son Siddhartan, who is a member of the People’s Liberation Organisation of Tamil Eelam militant group, blamed one of the members of Eelam National Liberation Front for the murders (PLOTE wasn’t a member of ENLF). The Sri Lankan government blamed the Liberation Tigers of Tamil Eelam for the murders. It is now widely believed that the murders were carried out by Tamil Eelam Liberation Organization, an Indian backed militant group, on the orders of the Research and Analysis Wing, the Indian intelligence agency. Alalasundaram was close to the TELO and a relative of its leader Sri Sabaratnam. It is believed that TELO chose to murder Alalasundaram at the same time as Dharmalingam so as to avoid suspicion