The man sentenced to 25 years in prison for the murder of Winnipeg teenager Candace Derksen has filed an appeal of his conviction and sentence.

Mark Edward Grant, 47, filed a lengthy appeal last week but the case isn't expected to go before the Court of Appeal until mid-fall, said a justice spokesperson.

Grant was found guilty of second-degree murder by a Queen's Bench jury on Feb. 18, following a five-week trial that focused on DNA evidence.

Grant's defence lawyer Saul Simmonds attacked the DNA evidence during the trial as faulty. At the time of the conviction, he told CBC News that an appeal was a certainty — it just had to wait until the sentencing process was completed.

That happened on May 26, when Chief Justice Glenn Joyal handed Grant a 25-year term.

Derksen, 13, was on her way home from school in November 1984 when she disappeared.

Her frozen body was found six weeks later, on Jan. 13, 1985, on the dirt floor of a rarely used supply shed in a brickyard about 500 metres from her family's East Kildonan home.

Her arms and legs were bound with rope and she was partially wrapped in blankets.

Three pubic hairs were found on or near her body, although police said she had not been sexually assaulted.

Four scalp hairs were also found but police weren't able to test them for DNA until technology improved in 1993.

Even then the technology was not good enough to determine a DNA profile, and Derksen's death remained a mystery until 2006, when police learned a lab in Thunder Bay had the ability to run more extensive hair-shaft DNA tests.

In May 2007 police came forward with new forensic evidence linking Grant with the murder scene.