The LaSalle Heights disaster occurred in the early morning of March 1, 1965 in the city of LaSalle, Quebec when a gas line explosion destroyed a number of low-cost housing units.
 In all, 28 people lost their lives, 39 were injured and 200 left homeless.
 Most of the casualties were women and children because many men had left for work.
 The casualties might have been higher had it not been the start of the month when many men left earlier than usual to pay their monthly rent at the rental office.
Ottis Elwood Toole (March 5, 1947 – September 15, 1996) was an American drifter and serial killer who was convicted of six counts of murder.
 Like his companion Henry Lee Lucas, Toole made confessions he later recanted, but which resulted in murder convictions.
 The discrediting of the case against Lucas for crimes in which Toole had offered corroborating statements created doubts as to whether either was a genuine serial killer or, as Hugh Aynesworth suggested, both were merely compliant interviewees whom police used to clear unsolved murders from the books.
 Toole received two death sentences, but on appeal they were commuted to life imprisonment.
 He died in his cell from cirrhosis, aged 49.
 Police attributed the murder of Adam Walsh to Toole on the basis of recanted statements.
 Lucas had backed Toole's confession to the Walsh murder, claiming he had been in possession of the victim's severed head.
Jeffrey Lionel Dahmer (May 21, 1960 – November 28, 1994), also known as the Milwaukee Cannibal, was an American serial killer and sex offender, who committed the rape, murder, and dismemberment of seventeen men and boys between 1978 and 1991.
 Many of his later murders involved necrophilia, cannibalism, and the permanent preservation of body parts—typically all or part of the skeletal structure.
Cold North Killers: Canadian Serial Murder is a 2012 Canadian non-fiction book written by Lee Mellor and published by Dundurn Press.
 It documents the lives of sixty Canadian serial killers, with the earliest being Edward H. Rulloff and the most recent being Russell Williams.
 The book uses Katherine Ramsland's interpretation of what constitutes a serial killer—someone who has killed at least two people on two separate occasions, and who attempted to or likely would have killed again—as outlined in her 2007 book "The Human Predator".
 "Cold North Killer's" own definition of what constitutes a Canadian serial killer includes both Canadians who committed murder abroad (such as Keith Hunter Jesperson and Gordon Stewart Northcott) and non-Canadians who committed murder in Canada (like William Dean Christenson and Earle Nelson).
Luis Alfredo Garavito Cubillos, also known as "La Bestia" ("The Beast") or "Tribilín" (named after Disney character "Goofy"'s Latin American Spanish name) is a Colombian rapist and serial killer.
 In 1999, he admitted to the rape, torture and murder of 147 young boys.
 His victims, based on the locations of skeletons listed on maps that Garavito drew in prison, could eventually exceed 300; Garavito continues to confess to more murders.
 He has been described by local media as "the world's worst serial killer".
 According to the Attorney General's Office and various judicial bodies, Luis Alfredo Garavito is the "second serial killer of the world."
 Likewise, the judicial body ruled that all Garavito's sentences total 1853 years and nine days in jail.
An Aso Oke Hat (pronounced ), a type of soft fez, is a traditional Yoruba hat that is made of hand woven Aso Oke, cotton, velvet, or damask.
 In the Yoruba language, this hat is called a fila.
 Although these hats originated in Nigeria they are worn by many men of African descent.
 Typically, the top of the hat slouches to one side, and rests above the wearer's ear.
 It is commonly worn with the Yoruba formal attire, Agbada (equally made with Aso Oke, lace or cotton) or brocade dashiki suits.
 Many men wear a bowler hat with the lace dashiki suit.
 However, an aso oke hat or crown style kufi cap are the most common choices when wearing any other type of formal attire.
John Balcerzak is a police officer in Milwaukee, Wisconsin and former president of the Milwaukee Police Association, having served in that post from 2005 to 2009.
 In 1991, he was fired for having handed over an injured child to serial killer Jeffrey Dahmer, despite a bystander's protests.
 He appealed his firing and was subsequently reinstated.
The July 2009 Ürümqi riots were a series of violent riots over several days that broke out on 5 July 2009 in Ürümqi, the capital city of the Xinjiang Uyghur Autonomous Region (XUAR), in northwestern People's Republic of China (PRC).
 The first day's rioting, which involved at least 1,000 Uyghurs, began as a protest but escalated into violent attacks that mainly targeted Han people.
 People's Armed Police were deployed, and two days later hundreds of Han people clashed with both police and Uyghurs.
 PRC officials said that a total of 197 people died, among those killed most of them are Hans, with 1,721 others injured and many vehicles and buildings destroyed; however, Uyghur exile groups say the death toll is higher.
 Many men disappeared during wide-scale police sweeps in the days following the riots; Human Rights Watch (HRW) documented 43 cases and said figures for real disappearances were likely to be much higher.
Randy Steven Kraft (born March 19, 1945) is an American serial killer known as the "Scorecard Killer" and the "Freeway Killer" who committed the rape, torture, mutilation, and murder of a minimum of 16 young men in a series of killings spanning between 1972 and 1983, the majority of which had been committed in California.
 Kraft is also believed to have committed the rape and murder of up to 51 further boys and young men.
 He was convicted in May 1989 of murdering 16 victims and is currently incarcerated upon death row at San Quentin State Prison in Marin County, California.
My Brother the Serial Killer is a 2012 American television documentary about serial killer Glen Rogers, otherwise known as the "Casanova Killer", who was convicted for a series of murders and arsons.
 The documentary was narrated by Rogers' brother Clay Rogers and aired on Investigation Discovery in November 2012.
 "My Brother the Serial Killer" received widespread media attention for Clay's claims that his brother was responsible for the 1994 murders of Nicole Brown Simpson and Ronald Lyle Goldman.

Question: How many men and boys did the serial killer, in which John Balcerzak handed over an injured child to, murder?
Answer: seventeen