The Madman of the route (Spanish: El loco de la ruta) is the nickname given to an alleged serial killer active in Mar de Plata, Argentina from 1996 to 1999. The allegations claim that a single killer is responsible for the murders and disappearances of at least 14 prostitutes, some of which were later found raped and mutilated near highways, sometimes with words written on their bodies.
 Since the emergence of this theory, several suspects have been proposed and charged, including a group of corrupt police officers, but none were convicted. To date, none of the murders have been definitively solved.
 On November 29, 1995, the body of 35-year-old María Esther Amaro was found on the side of Provincial Route 55. She had been strangled, and the word puta (bitch) had been written on her back with a sharp object, presumably a knife.
 On December 1, 1996, the naked body of 26-year-old Adriana Jaqueline Fernández, an artisan and prostitute from Uruguay, was found under a bridge along National Route 226. She had been strangled. Suspicions initially fell on her ex-boyfriend, who had previously served a sentence for murder, but there was insufficient evidence to charge him.
 On January 21, 1997, police located a torso and two arms along Provincial Route 88, but were unable to find the other remains. The body parts were identified as those of 26-year-old Viviana Guadalupe Espinosa Spíndola, a local prostitute who had recently gone missing. On May 13, the body of another prostitute, 27-year-old Mariela Elizabeth Giménez, was also found along Provincial Route 88. Like Espinosa, her arms had been cut off and she had cuts on her buttocks, but was determined to have been manually strangled. Hours after the discovery, a bouquet of flowers was found at the crime scene, which was later determined to be the work of a crime scene photographer who had offered his condolences.
 The last confirmed homicide attributed to the Madman took place on October 20, 1998. On that day, the legs of 25-year-old María del Carmen Leguizamón were found on Provincial Route 88, near Barrio Las Heras. The rest of her body was never found.
 Additionally, between July 21, 1997, and 1999, a total of nine other prostitutes disappeared: Ana María Nores, Patricia Angélica Prieto, Silvana Paola Caraballo, Claudia Jacqueline Romero, Verónica Andrea Chávez, Mirta Bordón, Sandra Villanueva, Mercedes Almaraz and Fernanda Varón. Despite the fact that they have never been found, their disappearances are also attributed to the Madman.
 In response to the crimes, the Ministry of Justice and Security announced a reward of 30,000 pesos for anyone who could provide information leading to the killer's arrest. This was later increased to 500,000 pesos.
 In 1997, the Buenos Aires Police Department created a "Serial Homicide Division" and asked for advice from the FBI and the French National Police.
 The first leads came from interviewing witnesses who had last seen the victims. According to some of them, they had seen a burgundy Ford Galaxy cruising the area at the time of the crimes, and in at least two cases (those of Amaro and Nores), they had seen the victims enter the vehicle. The witnesses described the man as about 45 years of age, stocky, balding and with some blonde hair left. On June 26, 1997, police seized the car of José Luis Andújar, the owner of a disco located along the Provincial Route 88. After examining his car for three days, traces of blood and black-colored hair were found on the carpet. Genetic tests concluded that they were of human origin, but had no relation to the deaths and disappearances.
 On the day of Chávez's disappearance, the 25-year-old was last seen attending her job as a checkroom attendant at a dance club in Mar de Plata. Days later, a diary with the names and telephone numbers of her regular clients were found inside her home. Among them were police officers and politicians, including prosecutor Marcelo García Berro. As a result, Judge Pedro Hooft ordered to intercept all registered phone numbers and to investigate all calls from the Salta 1337 brothel, where at least three of the twelve victims worked.
 On August 9, Hooft ordered the arrest of ten police officers and four civilians who were formally accused in the disappearances of Nores, Chávez and Caraballo. They were also investigated for involvement in the other cases, but were never tried for lack of evidence. The group was allegedly led by lieutenant Alberto Adrián Iturburu and protected by Berro. According to the case file, the gang was in charge of extorting prostitutes by forcing them to pay 100 pesos in order to "protect" and let them work. Thus, in theory, those who did not pay or wanted out of the deal would be killed.
 Despite the investigators' best efforts, the gang could never be linked to the three disappearances, nor to the other deaths, and were acquitted in 2004. To this day, all murders and disappearances linked to this case remain unsolved.
 In 2007, the mystery novel The Seer's Prayer (Spanish: La plegaria del vidente), written by Carlos Balmaceda, was published. It was inspired by the case, and in 2011, it was adapted into film.
 The song 'Desmembrado', released by Argentine death metal band Morferus in 2019, is also inspired by this case.