However authorities won't give details of him. His mother is also a leader in mobilizing families of missing persons in her neighborhood, the activist said.
Police spokesman Ajith Rohana said Jeyakumari was arrested for harbouring a criminal who he says was hiding at her home and shot at officers during a raid. He claimed the daughter was not arrested but taken in "for her own protection."
Tamil National Alliance the major political party representing ethnic Tamils had earlier expressed fear for their safety because officials had not brought them to court soon enough.
The rights activist said several family members of missing persons in Sri Lanka's former war zone have been silenced after being arrested under fabricated charges.