KEY POINTS:
Police are willing to offer the people who dumped Katrina Jefferies' body immunity from prosecution if they will name the young mother's killer.
A $50,000 reward has been offered this week for any information leading to the 22-year-old's killer.
Part of that reward included an offer of immunity
for any accomplice who is not the principal offender and Detective Senior Sergeant Gerry Whitley said that might apply to the person or people who helped dump Ms Jefferies' body.
A final decision about immunity from prosecution could only be made by the Solicitor-General, but this was an ideal opportunity for someone who might have witnessed the murder or dumped the body to clear their conscience and possibly avoid prosecution.
"They are my prime candidates for the immunity and/or the $50,000 reward."
Ms Jefferies' semi-naked body was found covered by a yellow raincoat, red tarpaulin and old painting down a bank at Waikowhai Reserve on Tuesday, July 12, 2005.
Speaking to the media yesterday, Ms Jefferies' mother, Nicola Jefferies, pleaded for anyone with information to come forward so her daughter's killer could be caught.
"Please give any information you have to the police, it's really important," she said. "If you had something to do with Katrina's death I really, really need you to help us solve this homicide."
Nicola Jefferies, who now cares for her daughter's 3 1/2-year-old son James, said the past two years had been difficult.
"It's really hard for us. I still miss her every day. I think about her all the time and wonder what happened to her but we are doing the best we can to carry on."
Her grandson was getting to the age where he was starting to realise he didn't have a mother.
"He's working out who I am [and asks] 'how come some people have a mummy and I have a nana?' I just say, well, I'm the person who takes care of you - I'm nana. You have a mummy but she's not here right now and nana will take care of you."
Nicola Jefferies said she manages by thinking about the good times she shared with her daughter, including nights together at home watching their favourite comedies, such as Friends.
She tries not to dwell on the bad but said if she could talk to the killer she would say she was hurt, angry and disgusted that her daughter was so brutally murdered.
Police have received 15 phone calls since the reward was offered on Monday. Mr Whitley said they were still waiting for that one "magic call" that would lead to the killer.
* Anyone with information is asked to call 0800 924 569.