:That is simply not true. Legal proceedings were controversially dropped and nobody was exonerated. The coroner's inquest resulted in a bizarre finding that Pinelli had neither jumped deliberately (as the police maintained) nor been thrown, but had fallen by accident; this was widely ridiculed. The scare quotes are indeed meant to cast suspicion, or more properly, to point out that suspicion was widely cast by reliable and significant sources. For example: 

 Giuseppe Pinelli and Pietro Valpreda were two anarchists arrested in the aftermath of the Hot Autumn Piazza Fontana bombing of November 12, 1969. Pinelli, a forty-one-year-old railway worker, was married with two daughters. Valpreda was a ballet dancer. Within seventy-two hours of his arrest, Pinelli was dead under suspicious circumstances. According to police statements, he had thrown himself from a window while being interrogated. However, there were discrepancies in the policemen's stories and in the evidence. At an inquest, suicide was not concluded; the death was deemed an accident. [...] A plaque dedicated to Pinelli can still be seen in Piazza Fontana, as most Italians believe he was a victim of police brutality. 
 Answers.Com 

 Accused of terrorism, Pinelli is said to have jumped to his death from the fourth-floor window of Milan police headquarters. Fo suspected, and a later investigation proved, that Pinelli was pushed out the window by the police. 
 TIME Magazine 

 In a Milan bank, a bomb killed 16 people and wounded more than 90. Initial police suspicion fell upon the far left, especially the anarchists. One anarchist, Giuseppe Pinelli, died in mysterious circumstances after “falling” from a fourth-floor window of Milan’s central police station. 
 Britannica 

 :Reliable sources, you know. Anyway I will see about some type of more informative wording.