While he had a bone to pick with the city's mayor, Sergei Bozhenov, who had beaten him in the October elections, he also claimed local investigators were trying to muzzle him and his colleagues in the opposition over allegations of official corruption.
Local investigators have disputed some of those claims, however.
Shein and five of his supporters began their fast on March 17 -- and within four days they claimed they had tasted success.
Officials from the federal Prosecutor General's Office have now pledged to take personal responsibility for the investigations against the would-be whistle-blowers under their personal control.
"The hunger strike was without doubt a success. Not only were our complaints heard, but we got [support]," Oleg Shein, a former Just Russia State Duma deputy,informed. "Our assessment of the situation coincided with their assessment. Even before we met them, they took the time to go over each case thoroughly," he said of officials in a special commission of the federal Prosecutor General's Office who traveled to the southern city to hear the case on March 20.
The Prosecutor General's Office could neither confirm nor deny these reports.
However independent analyst Vladimir Pribylovsky argued that it was too early for the protestors to claim a real triumph against the authorities, and noted Astrakhan's reputation as a city with one of the country's most murky business environments.
Concern from prosecutors would not necessarily translate into the cases being dropped, he said.
And although Shein is a prominent and popular figure in his hometown - pulling in 26 per cent of the vote on Oct. 11 amid claims of ballot-rigging - on a national level he remains obscure.
"If you dig into what goes on in the Astrakhan administration, you will unearth so many skeletons, and yes, that could be a powerful political playing card," Pribylovsky said. "But it's questionable whether the Kremlin would want to pursue such populist measures."
The October ballot turned Astrakhan into a hot spot for political conflicts that have been bubbling away in local administrations across the country, with the ruling United Russia party increasingly feeling the pressure of social tension due to the economic crisis.
As a result, analysts say the Kremlin allowed steam to be let off during the March 14 elections. In the southern Siberian town of Irkutsk, for instance, Communist-backed candidate Viktor Kondrashev managed to oust United Russia and became mayor.
And Shein's hunger strike has highlighted a heated battle between local investigators and opposition supporters in the aftermath of October's regional elections, widely described as some of the dirtiest Russia has seen in recent years.
It also underlined an escalating struggle for political influence in regional governments, as allegations of corruption against local officials become more virulent and widespread.
The cases in question include that of journalist Vladimir Anikin, a vocal critic of Astrakhan's mayor. In a December article published in his newspaper, Anikin alleged that the local Investigative Committee of the Prosecutor's Office bought a four-storey brick building from the mayor's wife for the equivalent of 10 million euros.
Shein and Anikin claim that the mayor had local investigators launch a criminal case against Anikin, who was called in for questioning about where he got the information about the real estate deal.
"The mayor should have applied as a citizen to a civil court," Anikin told The Moscow News. "Instead, he asked his friend, the director of the local investigative committee, to have a criminal libel case launched against me. It got to a point where he tried to get me prosecuted for jokes about the mayor that I published in my paper."
Asked about where got information about the deal, Anikin said it was from informed sources close to the case who talked to him on condition of anonymity.
Local parliamentarian Yevgeny Dunayev is also facing libel charges for criticising the mayor, Shein said.
Local investigators confirmed that they opened a criminal investigation against Anikin on claims from Bozhenov. The charges, however, were not libel but defamation of character.
Indeed, Anikin's article was virulently critical of local law enforcement, equating corrupt police and investigators with child molestors.
"And this is the person that Shein supported in his hunger strike," investigators added in an official statement provided.In another twist suggesting the level of corruption in Astrakhan's local political scene, the Astrakhan investigative committee has said that the "the hunger strike... was held in the Astrakhan Regional Duma, whose chairman, Alexander Klykanov, is on poor terms with the investigative directorate because his nephew... a police officer in the regional police department, has already been convicted of abuse of authority and is currently under investigation for his involvement" in a criminal gang that carried out paid killings.
The Astrakhan mayor's office refused to comment about the cases or about allegations related to the real estate sale.
Shein says that because of the legal separation of the Investigative Committee from the Prosecutor General's Office, prosecutors cannot actually stop the cases against the activists.
However, the high-level supervision of the investigation "will allow prosecutors to look at the cases objectively and it will help people in Moscow understand why local investigators don't want to look into corruption that takes place in Astrakhan," Shein said.