Rongo University student Sharon Otieno could have been raped before she was brutally killed, police have said.
An officer involved in the investigation yesterday said that used condoms were found at the scene of the pregnant student's murder.
"We found four used condoms and a pool of blood at the scene," said the officer.
The 26-year-old's body was found in a thicket near Wire Forest, about 50 metres from the Oyugis-Kisumu road, on Monday night, hours after she was kidnapped in Migori County alongside Nation Media Group journalist Barack Oduor.
Police said they were hot on the trail of three people suspected to have been involved in the kidnapping and murder of the student.
Other sources indicated the search for the suspects had spread to Nairobi, where some of the culprits were believed to be hiding.
A team of detectives visited Kayole, where they were informed one or two suspects could be hiding, but no arrests were made.
The vehicle the suspects were said to have used was also missing. The only person police are holding is Michael Oyamo, Migori Governor Okoth Obado's personal assistant.
Detectives said they had established that there had been communication between Mr Oyamo, the deceased and other persons who have not yet been arrested.
The manner in which blood splattered on guava leaves and grass, sources said, suggested there was a struggle as Sharon was being killed.
At the Rachuonyo Hospital in Homa Bay, mortuary, attendants told The Standard that Sharon's body was "in bad shape" when police brought it in.
"There were several stab wounds on the back, ear and abdomen. The neck was broken," said one of the attendants.
A postmortem examination is expected to be carried out today to establish the cause of the death.
As investigations progressed, police tightened security around the cell at the Homa Bay Police Station where Oyamo was being held.
"We are not taking any chances given what happened in Nairobi recently when a suspect was found dead in his cell. Our suspect is under tight security day and night," said a CID officer.
Yesterday afternoon, 10 detectives led by the Homa Bay County Directorate of Criminal Investigations Commander Daniel Wachira and his colleagues from Nairobi, visited the scene where Sharon's body was found.
CID officers, who included those sent from the special homicide squad in Nairobi, collected samples at the scene and visited the mortuary to view the body.
They also interacted with the residents to get more information regarding the murder.
Accounts by the Nation journalist indicated that besides Oyamo, there were three other people involved in the kidnapping - the driver of the vehicle and two other men.
Also at the mortuary were Sharon's relatives, including her mother, Melinda Auma, who declined to speak to journalists.
Nyanza Regional County Commander Leonard Katana told The Standard no further arrests had been made.
"We have launched a massive manhunt for the other people who were in the vehicle used in the kidnapping. We expect some more arrests soon."
Police are following leads that the vehicle - believed to be a Toyota Wish - might have been driven across the border to Tanzania.
Oyamo will have to wait until Monday to know whether or not he will be freed on bail after police secured a court order allowing them to detain him at Homa Bay Police Station as they conduct further investigations.
A senior police officer said detectives had made good progress in the investigation, but did not say whether other people apart from Oyamo had been questioned.
CID officers briefly presented Oyamo before a Homa Bay Court on Wednesday evening and sought the orders to continue holding him.
The aide was arrested after being implicated in the abduction of the Nation journalist and Sharon on Monday night.
Sharon was studying medical records and information at Rongo University in Migori.
In an affidavit sworn by Hassan Siyad, a police officer attached to the Directorate of Criminal Investigations, Oyamo was accused of murdering or causing the murder of Sharon.
“I believe Oyamo and other suspects involved in the abduction and murder have intentions which could be a threat to national security and public tranquility,” said Mr Siyad.
The investigator said the matter was too complex, hence the investigations could not be completed within 24 hours after Oyamo's arrest on Tuesday.
He was presenting the application to abide by the law which requires that a suspect should not be detained in police cells beyond 24 hours after.
He therefore appealed to the court to allow them detain Oyamo for 14 days.
“I notify this court of the arrest and due to technicalities involved in the investigations, I pray to the court that he be detained at Homa Bay Police Station for 14 days to enable us complete the investigations,” Siyad added.
Homa Bay Deputy Registrar Lester Simiyu granted police more time to continue detaining Oyamo.
However, she gave them until Monday to return him to court.
At Sharon's parents' home, family members met to plan her burial.
[Report by James Omoro, Cynthia Otieno and Dalton Nyabundi and Cyrus Ombati]