A federal jury blamed three aging mobsters for 10 murders Thursday, after an extraordinary trial that included a parade of colorful witnesses who exposed the seedy inner workings of organized crime in Chicago.

Jurors deadlocked on blame for eight other murders after eight days of deliberations in one of the biggest mob trials in the city's storied crime history.

But prosecutors won the murder convictions they coveted against Frank Calabrese Sr., Joseph "Joey the Clown" Lombardo and James Marcello, increasing the maximum sentence each of them faces to life. Jurors deadlocked on the fourth defendant, Paul Schiro.

U.S. District Judge James B. Zagel polled individual jurors, and all said further deliberations would not help them come to a unanimous decision on the deadlocked counts.

The same jury convicted five men on Sept. 10 of taking part in a racketeering conspiracy that involved illegal gambling, loan sharking, extortion and a wave of mob murders going back almost four decades.

The jury then considered whether four of the five men were individually responsible for specific murders — the prerequisite for toughening their sentences to life.

Those convicted of racketeering conspiracy were Marcello, 65, Calabrese, 70, Lombardo, 78, Schiro, 70, and retired police officer Anthony Doyle, 62.

All but Doyle were accused in the indictment of having committed specific murders. Doyle is not accused of direct involvement in a murder.

The so-called Operation Family Secrets trial is the biggest organized crime case in Chicago in many years. The defendants were convicted of operating the Chicago Outfit, as the city's organized crime family is called, as a racketeering enterprise.

They allegedly squeezed "street tax," similar to protection money, out of businesses, ran sports bookmaking and video poker businesses as well as engaged in loan sharking. And they allegedly killed many of those who might have spilled their secrets to the government.

The oldest murder listed in the indictment, that of Michael "Hambone" Albergo, himself a loan shark, goes back to 1970.