Longtime police detective Lou Smit, who first investigated and then supported JonBenet Ramsey's parents, has died, a hospice spokeswoman confirmed Thursday. Smit, 75, had cancer and died Wednesday at Pikes Peak Hospice in Colorado Springs. Hospice spokeswoman Robin Witten said he had a steady stream of visitors. Smit's long career included years as an investigator for the Colorado Springs Police Department and the El Paso County sheriff's office, where he was captain of detectives. His dogged police work was credited with helping lock up more than 200 killers. He became known nationally when he was coaxed out of retirement to help investigate the 1996 death of 6-year-old JonBenet Ramsey, who was found beaten and strangled in the basement of her parent's Boulder home Dec. 26, 1996. Smit later resigned because he believed authorities were wrongly focusing on the parents, John and Patsy Ramsey. Smit said unidentified DNA under JonBenet's fingernails and on her underpants pointed to an intruder as the culprit, not her parents. He later worked for the Ramseys. "The point is there is foreign DNA. There is common foreign DNA. It is not John. It is not Patsy. It is not (JonBenet's brother) Burke," Smit said in a 2001 interview. "So just to take this and say it's degraded and throw these beautiful clues away, you can't do it. You have to plug these clues into the intruder side of the story as well." In 2008, former Boulder County District Attorney Mary Lacy publicly exonerated JonBenet's family in the girl's death. Patsy Ramsey died of ovarian cancer in 2006 in Atlanta, where the family moved after JonBenet's death. Smit helped solve other high-profile slayings in Colorado, including the 1975 rape and murder of Karen Elisa Grammer, the sister of actor Kelsey Grammer. Freddie Glenn was convicted in her abduction, rape and murder. Smit was hired out of retirement in 1995 to help solve the slaying of 13-year-old Heather Dawn Church, who was abducted from her El Paso County home in 1991. Robert C. Browne pleaded guilty to first-degree murder in the case and was sentenced to life in prison.In 2008, he told 7NEWS he knew from the beginning that the Ramseys were innocent and he still hoped the real killer would be found. Smit helped solve other high-profile slayings in Colorado, including the 1975 rape and murder of Karen Elisa Grammer, the sister of actor Kelsey Grammer.In 2002, author Robert Wise wrote a book called "Dead Detective" based on Lou Smit.