Last year, he tried to bring NFL superstar Tim Tebow to Moscow to play for his American football team on a $1 million-per-game contract. Now, accused of breaking a window, American businessman Mike Zaltsman shares a packed jail cell with drug dealers.

Much has changed for the Boston entrepreneur since a dispute over an office he rented from a Russian billionaire escalated into a weeks-long standoff in downtown Moscow and ended with his arrest in April.

The case puts into relief the unpredictable business environment in Russia, where thousands of people have ended up in jail as the result of business disputes or raids by business rivals. Even seemingly petty crimes are routinely used to keep people in Russian prisons for months or even years.

It is difficult to determine who is right and who wrong in the murky property dispute. But Zaltsman's treatment, advocates say, is excessive by any standard: "The fact that he was jailed for a broken window — this is cruel and sadly typical of Russia," said Yana Yakovleva, founder of the advocacy group Business Solidarity. Moscow police and investigators refused to comment on the Zaltsman case.

Zaltsman, who has dual Russian and U.S. citizenship, was accused of hooliganism — the same charge leveled against members of the feminist punk band Pussy Riot, landing them in a remote prison camp. If convicted, he could be imprisoned for up to seven years.

The entrepreneur, who denies allegations he was delinquent on his rent, says he has had no contact with U.S. Embassy officials. A State Department official, speaking on condition of anonymity because he is not authorized to speak to the media, disputed this. He said U.S. diplomats have been in contact with Zaltsman and were monitoring the case.

Zaltsman's jailing coincided with escalating tensions between Moscow and Washington over Ukraine, which were accompanied by a sharp rise in Russia of anti-American sentiment and suspicion of U.S. intentions. In St. Petersburg this fall, four U.S. students were detained for hours during a leadership conference, while two American journalists were briefly detained while teaching an investigative journalism workshop. In both cases, the Americans were accused of having the wrong type of visa.

There has been no suggestion that these tensions played a role in the Zaltsman case, however.

Zaltsman grew up in Russia before moving to Boston in 1996 at age 19 with his parents as one of many Russian Jews to leave the chaos and poverty of their home country in the aftermath of the Soviet Union's collapse. He became a U.S. citizen five years later.

After brief periods studying at Northeastern University and operating a Russian bookshop in Boston, ventures in shipping and media helped him amass a fortune he values at $10 million. He moved back to Russia in 2005, using his money to build his Black Storm football team, which last year had six American pros on the roster as it won the Russian championship. He failed, however, in his audacious bid to sign former Denver Broncos quarterback Tebow.

Until recently Zaltsman, 37, divided his time between Los Angeles, Boston and Moscow. Now home is Moscow's pre-trial Detention Facility No. 5. Seven months since his arrest, Zaltsman says he shares a crowded cell with up to 15 others, with no sign of a trial. Floor space per prisoner, he says, is just 21 square feet, barely enough to lie down.

"Almost no sky and sun can be seen here," he said. "I'm forgetting how it looks."

Dmitry Popkov, the former coach of Zaltsman's team, was arrested with him. He suffers from a chronic health condition, which led to the botched removal of his gallbladder while in jail and left him in constant pain. In October, Popkov pleaded guilty in order to leave jail and receive treatment while under house arrest.

"Serious health issues that I had have gotten worse while I have been in jail," Popkov said in a written statement shortly before his release. "I will have to plead guilty to the crime that I did not commit at the next hearing to extend my time in jail. Right now this is the only way for me to get out of prison."

There are sharply contrasting versions of how Zaltsman came to be in jail.

Zaltsman claims he was persecuted by Andrei Gorodilov, a publicity-shy tycoon who counts London-based billionaire Roman Abramovich, owner of the Chelsea football club, as a longtime business partner and friend. Neither Gorodilov nor his representatives agreed to comment for this story.

Abramovich testified in 2011 during a high-profile London trial that Gorodilov helped him seal the business deal that made his name and fortune: the creation of the oil company Sibneft in the 1990s. Abramovich later sold 75 percent of Sibneft to Russian state firm Gazprom for $13 billion. Gorodilov briefly entered politics with Abramovich, serving as his deputy during his time as governor of the remote Chukotka region.

In August 2013, a company controlled by Zaltsman signed a five-year lease on an office in one of Moscow's most upscale neighborhoods from a businesswoman associated with Gorodilov. Within a few months, Zaltsman says, he came under pressure to break the lease from Gorodilov, who took over as the registered owner of the property as the dispute escalated.

When talks broke down, Zaltsman claims, Gorodilov sent about 30 men, some armed, to occupy the office and smash furniture belonging to Zaltsman's businesses. Zaltsman also claims they stole office equipment worth around $20,000.

Kyle Israel, a Black Storm player who witnessed the events unfold, says he tried to dissuade Zaltsman from putting up a fight.

"I had told him: 'Hey, why don't you back off? Why do you do this?'" Israel recalls, but adds: "Once Mike had his mind made up about something, he is going to do what he believes he needs to do to make this come to fruition."

Zaltsman says he and some "friends" reacted first by filming the raiders and trying to generate publicity over what they saw as an attack. Then they moved to more aggressive methods.

On April 13, Zaltsman says, he and his supporters tried to execute a plan to scare Gorodilov's security into leaving the office. The Boston businessman himself shouted that he was from the SOBR police special forces — the Russian equivalent of SWAT — and that "anyone who doesn't leave in the next 10 seconds will be shot on the spot." The occupants left, but in the confusion, Zaltzman says, one threw a chair through a window.

Zaltsman and Popkov were arrested 10 days later. Zaltsman was accused of breaking the window himself, while his associate was accused of assaulting one of the security guards.

In two civil cases brought against Zaltsman, the courts sided with Gorodilov and said the eviction was legitimate. The court ruled that Zaltsman's company had stopped paying rent and had therefore ceased to be the legal tenant. Zaltsman insists he paid rent in compliance with the terms of the lease. Neither he nor his company was represented at some of the hearings.

While the criminal case is under investigation, police have refused to comment, after passing a written request from one office to another for weeks. They agreed only to provide the article of the criminal code under which the men are charged. It specifies that they are accused of hooliganism while acting as part of a group and resisting police or security guards.

In addition, Zaltsman is charged with failing to formally notify Russian authorities that he holds dual citizenship, under a law that came into force this summer when he was already in custody.

Dionis Dedov, Zaltsman's lawyer, said his client is a victim of capricious justice.

"He believed he was merely restoring his rights as a tenant since there were no court rulings ordering him to evict," Dedov said. "Even with the charges that have been put forward, the detention for such a long period of time seems excessive."