One of the cops has been recorded assuring the main accused, the woman's brother, who had begged on the phone: "I will fall at your feet."
The officer is heard replying: "I will do whatever possible."
Kevin Joseph was found dead after he was kidnapped late on Saturday night, just days after he and his girlfriend Neenu applied for a registered marriage.
Neenu's father and brother are among five people arrested since Kevin's body was found from a canal on Sunday.
Call records reveal that a police officer spoke to Neenu's brother several times, but never told his seniors.
A leaked phone audio conversation reveals how Neenu's brother pleaded with the officer: "It is a mistake ... We will pay for any damages... Do talk to Neenu and try for her to return to us. I will fall on your feet."
The cop is heard saying, "I will do whatever possible".
"It has emerged that the two cops helped the accused. Probe is underway and I cannot give out more details", senior police official Vijay Sakhare said today.
Two other relatives of Neenu, also are local leaders of the ruling CPM's youth wing DYFI, were also arrested.
A policeman suspended earlier has been accused by Kevin's parents and Neenu of saying, when they went to report Kevin missing, that he was "busy with the chief minister's security".
Kerala Chief Minister Pinarayi Vijayan, in a public address, claimed that the incident is being given political colours. "Instead of seeing the lapses of one police official, an attempt is being made to build a narrative that he was busy with Chief Minister's security arrangements. In fact right from the time this incident happened in early hours, till 3pm, these cops did not do what was required of them. There has been a lapse."
Opposition leaders from Congress and BJP have demanded Mr Vijayan's resignation, blaming him for what they call a "failure of law and order in the state".
Mr Vijayan is also in charge of the state home ministry.