Five people have been detained for questioning in connection with last week's murder in Ernakulam district.
Police said the autopsy report would determine whether the woman was raped.
Dalits, formerly known as untouchables, form the lowest rung of India's caste hierarchy.
The 30-year-old law student was found murdered in her house, where she was living with her mother, a casual labourer, in Kuruppampady village on Thursday. Her mother was away at work.
Reports said her body had several stab wounds, and her intestines had been pulled out during the attack.
Police have released a sketch of a suspect and said they were looking for a man seen leaving the victim's home, according to Reuters.
We can understand that people are very angry but we have very little evidence to find the accused," police official K Padmakumar told the agency. "We are doing our best."
The police detained seven men - including two friends, a colleague and the victim's dance teacher - for questioning. Two of them were let off later.
Kerala Chief Minister Oommen Chandy said the incident was "shocking" and the culprits "would be brought to book at the earliest".
"Such a brutal attack could not have happened in our state. This was barbaric."
Outraged over the incident, women have been holding protests over the past few days, demanding a speedy investigation.
They gathered outside the hospital on Tuesday where the victim's body had been taken, holding placards demanding justice for her.
On Wednesday, demonstrations were held in a town near the victim's village.
In a separate incident, police have arrested an auto-rickshaw driver for allegedly raping his 19-year-old friend, also a Dalit, in Trivandrum.
Last week's incident has drawn comparisons to the December 2012 gang rape of a woman on a Delhi bus that sparked widespread outrage and nationwide protests demanding an end to the widespread sexual assault and abuse of women across India.
Scrutiny of sexual violence in India has grown since the attack and the outrage that followed prompted the government to tighten the law.
But experts say tougher laws have failed to bring down the number of rape cases and a series of high-profile crimes have taken place since.
Police have used batons to disperse angry demonstrations in the southern Indian state of Kerala after the mutilated body of a student from the Dalit community was found in her home.