It smells very, very fishy...
Rudy and Donald first got together in the late 1980s shortly before Donald became a co-chair of Giuliani's first fundraiser for his 1989 mayoral campaign, sitting on the Waldorf dais and steering $41,000 to the campaign. A year earlier, Tony Lombardi, the federal agent closest to then-U.S. Attorney Giuliani, opened a probe of Trump's role in the suspect sale of two Trump Tower apartments to Robert Hopkins, the mob-connected head of the city's largest gambling ring.
Trump attended the closing himself and Hopkins arrived with a briefcase loaded with up to $200,000 in cash, a deposit the soon-to-felon counted at the table. Despite Hopkins' wholesale lack of verifiable income or assets, he got a loan from a Jersey bank that did business with Trump's casino. A Trump limo delivered the cash to the bank.
The government subsequently nailed Hopkins' mortgage broker, Frank LaMagra, on an unrelated charge and he offered to give up Donald, claiming Trump "participated" in the money-laundering — and volunteering to wear a wire on him.
Instead, Lombardi, who discussed the case with Giuliani personally (and with me for a 1993 Village Voice piece called "The Case of the Missing Case"), went straight to Donald for two hour-long interviews with him. Within weeks of the interviews, Donald announced he'd raise $2 million in a half hour if Rudy ran for mayor. Lamagra got no deal and was convicted, as was his mob associate, Louis (Louie HaHa) Attanasio, who was later also nailed for seven underworld murders. Hopkins was convicted of running his gambling operation partly out of the Trump Tower apartment, where he was arrested.
Lombardi — who expected a top appointment in a Giuliani mayoralty, conducted several other probes directly tied to Giuliani political opponents, and testified later that "every day I came to work I went to Mr. Giuliani to seek out what duties I needed to perform" — closed the Trump investigation without even giving it a case number. That meant that New Jersey gaming authorities would never know it existed.
[source : Peas in a pod: The long and twisted relationship between Donald Trump and Rudy Giuliani, New York Daily News, http://www.nydailynews.com/opinion/wayne-barrett-donald-trump-rudy-giuliani-peas-pod-article-1.2776357, 4th September 2016]
So it was Cohn who got Giuliani appointed as U S Attorney.
And when Trump could have been done for moneylaundering it looks like Giuliani let Trump off in return for 'donations'.
Life really is stranger than fiction.