A man was arrested on Saturday night for allegedly killing his 30-year-old girlfriend and burying her body in the backyard of his under-construction house, an official said.
Acting on a tip-off, police arrested Akhil, a prime accused in the case, from the Thiruvananthapuram International Airport, he said.
"We got information that he will reach the airport in the night. We were closely monitoring his movements. He is being interrogated and will be produced before the court tomorrow," the official told PTI.
According to police, Akhil and Rakhi were in a relationship for over six years and she started quarrelling with him when she got to know that he was getting married to another woman.
Then Akhil and his brother Rahul hatched a conspiracy to kill Rakhi. They strangulated her to death and buried the body in the backyard of their under-construction house, police said.
The matter came to light when police found the decomposed body of Rakhi on July 24.
Earlier in the day, police had arrested Rahul in connection with the case.
Besides Rahul and Akhil, their friend Adarsh, a suspect in the case, was also taken into custody, police said.