The 30-year-old university law student from a low social caste was attacked last Thursday at her home in the southern state of Kerala, with her mother discovering her body in a pool of blood.
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"The suspect attacked and murdered her brutally and fled the scene quickly," police inspector general Mahipal Yadav, who is heading the investigation, said of the case reported on Tuesday in national newspapers.
"There are indications that her intestines came out after severe violation by some foreign object," Yadav told AFP.
He said police suspect the victim was also raped but were awaiting a medical report.
Police also suspect the victim from the town of Perumbavoor, 220 kilometres (136 miles) north of state capital Thiruvananthapuram, knew her attacker because there was no signs of forced entry to her home, he said.
India's media drew comparisons on Tuesday with the attack on the Delhi student who was raped by a gang of six including with an iron rod as she returned home from the cinema.
The horrific nature of that crime drew global attention and unleashed seething public anger in India about high levels of sexual violence against its women.
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The incident led to an overhaul of India's rape laws, including the speeding up of trials and tougher penalties for offenders, but high numbers of assaults persist.
The latest official figures show 36,735 rapes were reported across the country in 2014, although activists say the actual number is likely much higher with many crimes going unreported due to the social stigma they attract.
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