Robert Christian Boes Hansen (February 15, 1939 – August 21, 2014), popularly known as the Butcher Baker, was an American serial killer active in Anchorage, Alaska, between 1972 and 1983. Hansen abducted, raped and murdered at least seventeen women, many of whom he hunted in the wilderness with a Ruger Mini-14 and a knife. Hansen was captured in 1983 and sentenced to 461 years' imprisonment without the possibility of parole. He died in 2014 of natural causes at age 75.
 Robert Hansen was born in Estherville, Iowa, on February 15, 1939, the eldest of two children to an American mother, Edna Margret Hansen (née Petersen; October 27, 1916 – April 24, 2005) and a Danish father, local baker Christian "Chris" Hansen (September 16, 1907 – August 12, 1983). Robert was employed at his father's bakery. The family moved to Richmond, California, in 1942, but returned to Iowa in 1949 and settled in Pocahontas. 
 In his youth, Hansen was painfully shy, had a stutter and suffered severe acne that left him permanently scarred. Throughout childhood and adolescence, he was described as a quiet loner who had a difficult relationship with his domineering father. Hansen started to practice both hunting and archery, often finding refuge in these pastimes. In 1957 he enlisted in the United States Army Reserve and served for one year before being discharged. He later worked as an assistant drill instructor at a police academy in Pocahontas. There, he began a relationship with a younger woman, whom he married in the summer of 1960.
 On December 7, 1960, Hansen was arrested for burning down a Pocahontas County school bus garage, as revenge for his unpopularity in high school. He served twenty months of a three-year prison sentence in Anamosa State Penitentiary. During his incarceration, he was diagnosed with manic depression with periodic schizophrenic episodes. The psychiatrist who made the diagnosis noted that Hansen had an "infantile personality" who was obsessed with getting back at people he felt had wronged him. Hansen's wife filed for divorce while he was incarcerated.
 Over the next few years, Hansen was jailed several times for petty theft. In 1967, he moved to Anchorage, Alaska, with his second wife, whom he had married in 1963 and with whom he had two children. In Anchorage, he was well liked by his neighbors and set several local hunting records.
 In December 1971, Hansen was arrested twice: first for abducting and attempting to rape an unidentified housewife and then for raping an unidentified prostitute. He pleaded no contest to assault with a deadly weapon in the former offense; the rape charge involving the prostitute was dropped as part of a plea bargain. Hansen was sentenced to five years in prison; after serving six months of his sentence, he was placed on a work release program and released to a halfway house. In 1976, Hansen pleaded guilty to larceny after he was caught stealing a chainsaw from an Anchorage Fred Meyer store. He was sentenced to five years in prison and required to receive psychiatric treatment for his bipolar disorder. The Alaska Supreme Court reduced his sentence, and he was released with time served.
 Hansen is believed to have begun killing around 1972. His modus operandi was to pick up a prostitute in his car and force her at gunpoint to his home, where he would rape her; he would then take her out to a secluded area and "hunt" her as if she were wild game before shooting or stabbing her. It is believed by authorities that Hansen's first murder victim was 18-year-old Celia van Zanten. Van Zanten was kidnapped on December 22, 1971, and froze to death in the wilderness after escaping from her abductor; her body was discovered on December 25. The abduction occurred three days after Hansen committed his assault on the prostitute for which he was imprisoned. While there are some similarities to Hansen's modus operandi and Van Zanten's abduction, there is no conclusive evidence linking him to the attack and he himself denied involvement.
 On June 13, 1983, Hansen offered 17-year-old Cindy Paulson $200 to perform oral sex; when she got into the car, he pulled out a gun and drove her to his home in Muldoon. There, he held her captive and proceeded to rape and torture her. She later told police that after Hansen chained her by the neck to a post in his basement, he took a nap on a nearby couch. When he awoke, he put her in his car and took her to Merrill Field airport, where he told her that he intended to "take her out to his cabin" (a shack in the Knik River area of the Matanuska-Susitna Valley accessible only by boat or bush plane). Paulson, crouched in the back seat of the car with her wrists cuffed in front of her body, saw a chance to escape when Hansen was busy loading the cockpit of his airplane, a Piper PA-18 Super Cub. While Hansen's back was turned, Paulson crawled out of the back seat, opened the driver's side door and ran toward nearby Sixth Avenue.
 Paulson later told police that she had left her blue sneakers on the passenger side floor of the sedan's backseat as evidence that she had been in Hansen's car. Hansen panicked and chased her, but Paulson reached Sixth Avenue and managed to flag down a passing truck. The driver, Robert Yount, alarmed by Paulson's disheveled appearance, stopped and picked her up. He drove her to the Mush Inn, where she jumped out of the truck and ran inside. While she pleaded with the clerk to phone her boyfriend at the Big Timber Motel, Yount continued on to work, where he called the police to report the incident.
 When Anchorage Police Department (APD) officers arrived at the Mush Inn, they were told that Paulson had taken a cab to the Big Timber Motel. APD officers arrived there and found Paulson in Room 110, still handcuffed and alone. She was taken to APD headquarters, where she described the perpetrator. Hansen, when questioned by APD officers, denied Paulson's accusation, stating that she was trying to cause trouble for him because he would not pay her extortion demands. Although he had several prior run-ins with the law, Hansen's meek demeanor and humble occupation as a baker, along with an alibi from his friend John Henning, kept him from being considered as a serious suspect.
 Detective Glenn Flothe of the Alaska State Troopers had been part of a team investigating the discovery of several bodies in and around Anchorage, Seward and the Matanuska-Susitna Valley area. The first of the bodies was found by construction workers near Eklutna Road. The body, dubbed Eklutna Annie by investigators, has never been identified. Later that year, the body of Joanna Messina was discovered in a gravel pit near Seward, and in 1982 the remains of 23-year-old Sherry Morrow were discovered in a shallow grave near the Knik River. Flothe believed all three women had been murdered by the same perpetrator.
 Flothe contacted Federal Bureau of Investigation (FBI) Special Agent John Douglas and requested help with an offender profile based on the three recovered bodies. Douglas thought the killer would be an experienced hunter with low self-esteem, have a history of being rejected by women, and would feel compelled to keep "souvenirs" of his murders, such as a victim's jewelry. He also suggested that the assailant might stutter. Using this profile, Flothe investigated possible suspects until he reached Hansen, who fit the profile and owned a plane.
 Supported by Paulson's testimony and Douglas' profile, Flothe and the APD secured a warrant to search Hansen's plane, vehicles and home. On October 27, 1983, investigators uncovered jewelry belonging to some of the missing women as well as an array of firearms in a corner hideaway of Hansen's attic, which included a .223-caliber Ruger Mini-14 semi-automatic rifle. Also found was an aeronautical chart with thirty-seven little "x" marks on it, hidden behind Hansen's headboard. Many of these marks matched sites where bodies had been found previously (others were discovered later at the locations marked on Hansen's murder map).
 When confronted with the evidence found in his home, Hansen denied it as long as he could, but he eventually began to blame the women and tried to justify his actions. Eventually confessing to each item of evidence as it was presented to him, he admitted to a spree of attacks against Alaskan women starting in 1971. Hansen's earliest victims were girls or young women, usually between ages 16 and 19 and not prostitutes, unlike the victims who led to his discovery.
 Hansen is known to have raped and assaulted over thirty Alaskan women and to have murdered at least seventeen, ranging in age from 16 to 41, although based on evidence law enforcement suspect that Hansen killed at least twenty-one female victims. 
The following is a list of Hansen's known victims and several other additional women who have been mentioned as possible victims. Of these eighteen women, Hansen was only formally charged with the murders of four: Sherry Morrow, Joanna Messina, Eklutna Annie and Paula Goulding. He was also charged with the kidnapping and rape of Cindy Paulson.
 Once arrested, Hansen was charged with assault, kidnapping, multiple weapons offenses, theft and insurance fraud. The last charge was related to a claim filed with the insurance company over the alleged theft of some trophies; he used the proceeds to purchase his plane. At trial, he claimed he later recovered the trophies in his backyard but forgot to inform the insurer.
 Hansen entered into a plea bargain after ballistics tests returned a match between bullets found at the crime scenes and Hansen's rifle. He pleaded guilty to the four homicides the police had evidence for (Morrow, Messina, Goulding, and Eklutna Annie) and provided details about his other victims in return for serving his sentence in a federal prison, along with no publicity in the press. Another condition of the plea bargain was his participation in deciphering the markings on his aviation map and locating his victims' bodies. Hansen confirmed the police theory of how the women were abducted, adding that he would sometimes let a potential victim go if she convinced him that she would not report him to police. He indicated that he began killing in the early 1970s.
 Hansen showed investigators 17 grave sites in and around Southcentral Alaska, 12 of which were unknown to investigators. There remained marks on his map that he refused to give up, including three in Resurrection Bay, near Seward. Authorities suspect two of these marks are the graves of Mary Thill and Megan Emrick, whom Hansen has denied killing. The remains of 12 of a probable 21 to 37 victims were exhumed by the police and returned to their families.
 Hansen was sentenced to 461 years in prison without the possibility of parole. He was first imprisoned at the United States Penitentiary, Lewisburg in Lewisburg, Pennsylvania. In 1988, he was returned to Alaska and briefly incarcerated at Lemon Creek Correctional Center in Juneau. He was also imprisoned at Spring Creek Correctional Center in Seward until May 2014, when he was transported to the Anchorage Correctional Complex for health reasons. Hansen died on August 21, 2014, age 75, at Alaska Regional Hospital in Anchorage due to natural causes related to lingering health conditions.