The 29-year-old lady constable had grown frustrated and committed suicide a few days ago, following the refusal of the accused to marry her, they said.
The accused and the victim had developed intimacy when they were working in Alangulam division in this district.
The constable had physical relationship with the woman under the pretext of marrying her.
When she insisted on getting married, he kept delaying the marriage, they said.
Arumainayagam who had gone absconding was arrested here today, they added.