As a crime boss, he developed a system in which he would guarantee the city's gambling dens and brothels protection from interference in exchange for payment.

[3][4] The elder McDonald then worked in Quebec as a laborer,[3] before immigrating again into the United States, settling in Niagara County in 1837.

[9] During the American Civil War, he organized groups of fraudulent enlistees who enlisted under false aliases multiple times to collect the $500 bounties.

[10] In this scheme, he colluded with army deserters, who had agreed to turn themselves in, to then reenlist, and then split the commission which McDonald received for recruiting them.

After having spent some time financing a traveling faro bank, in 1867, McDonald opened his first gambling establishment at 89 Dearborn street.

[11] In November 1868, the Chicago Tribune reported McDonald's arrest, along with national billiards champion John McDevitt and two other gamblers, for criminal conspiracy and the running of gambling dens after having apparently fleeced an intoxicated man out of more than $400 while playing faro.

McDonald was unable to afford bail, and, consequentially, spent three months in prison prior to being acquitted at his trial.

[19] Some sources attribute the origin of the famous phrase "there's a sucker born every minute" to McDonald, who reportedly said it in response to concerns a crony voiced about whether the parlor could attract enough costumers to fill the large number of gaming tables in the venue.

[1][20][19] McDonald developed a system under which he was paid tribute by the city's gambling establishments and brothels, and, in exchange, would use his influence to ensure that they could operate without police interference.

[20] In 1873, by which time McDonald was well-established in the criminal underbelly of Chicago, he organized the successful mayoral campaign of his close friend Harvey Doolittle Colvin.

[20] McDonald's political influence experienced a setback when Chicago elected reform mayor Monroe Heath in 1876.

[20] By the peak of his influence, he would receive the nickname "King Mike", and would brag that he "ran the town" and had the city's police department "under his thumb".

[20] McDonald established an alliance between the city's gambling interests and its politicians which saw some illegal gaming revenue used to fund Democratic Party political operations.

Mary hated cops, and fired a gunshot from a pistol that pierced a police officer's coat, but missed him.

She also dropped an iron bar down the stairs onto another policeman, injuring his back, but despite some later claims that she killed a cop during the raid, an article in the Chicago Tribune states otherwise.

[30][10][31] She was arrested and charged with assault with intent to kill, but on December 2 the judge dismissed the case because he said the police violated the law by raiding a private residence without a warrant.

[33] After the shooting incident, McDonald moved his wife and two children out of "The Store" and into a mansion that was built for them on Ashland Avenue, near Mayor Harrison's own residence.

[31] However, months later, Mary McDonald left her husband to pursue a relationship with a notable minstrel singer in San Francisco.

[17] At a private meeting held at the White House, McDonald was able to convince Chester A. Arthur to pardon a colleague of his who had been convicted in a pyramid scheme.

[33][41] However, this created scandal after a newspaper investigation discovered this, and it tarnished McDonald's image, leaving him with the local title of "King of the Boodlers".

[41] In 1887, as a result of this scandal, former General Superintendent of the Chicago Police Department Wiliam J. McGargile was convicted of complicity in a Cook County graft ring, including bribes from McDonald.

[41] The tarnish of scandal in which McDonald had found himself in was another contributing factor to Carter Harrison's decision not to run in the 1887 mayoral election.

Mary busied herself with religion, even building an altar in their Ashland Avenue home and having a private priest hired to administer sacred rights and say mass.

[55] Cregier would win renomination, but would lose the general election after Harrison ran an independent campaign, helping to split the Democratic Party vote.

[34][63] Moreover, at the time McDonald began a public affair with her, she was married to professional baseball player Sam Barkley.

[66] At the age of 19, McDonald's son Guy, wanting to escape the drama-filled household, married his girlfriend over his father's objections and threats to disinherit him if he did.

[1][34][67] On February 21, 1907, Dora Feldman McDonald went to Guerin's picture studio in Chicago Loop, where an argument broke out between the two.

[1][62] Five minutes after she shot Guerin, police officer Clifton Woodridge (one of Chicago's top detectives) arrived at the studio, having, unrelatedly, come to investigate reports of questionable business practices.

[69] Dora Feldman McDonald's mental health condition worsened while she was in jail awaiting trial, and some close to her feared her to be suicidal.

McDonald's elegant and flamboyant dress inspired the appearance of the character Gaylord Ravenal in Edna Ferber's 1926 book Show Boat.