Thieves have struck again at St Petersburg's Russian National Library, stealing four tomes worth over $1 million.
St Petersburg police announced last Friday that four books from the 19th century series "Birds of America" were missing.
It is the third major theft from the library in the last year.
More than 90 ancient Tibetan, Mongolian and Chinese texts, worth an estimated $700 million, were stolen last December.
Detectives from the Federal Counter-intelligence Service (FSK) soon recovered the manuscripts and Moscow-based lawyer Dmitri Yakubovsky was later charged in connection with the heist.
That theft was discovered only three days after 18 rare books were returned to the library on December 8, 1994.
The "Birds of America" books were missed last Wednesday when it was realized that all the pages of the richly illustrated texts had been removed. Only the covers remained of the original books.
Police and library officials have refused to comment on the crime.
The tomes were removed from a section of the library on Ploshchad Ostrovskovo not open to the general public.
All staff and any authorized researchers must pass through security checkpoints. It is believed the thief or thieves smuggled the book pages out of the section past the guards.
This is the same part of the library from which the 18 books stolen last year were removed.
Among those books -- returned by FSK officers last December -- were tomes with drawings of rare animals.
Local media have said that the heist looks like another inside job performed in response to a request for these specific books.
Sources have estimated the stolen books' value on the black market at over $1 million.
The theft came just days after the St Petersburg city prosecutor announced that charges had been filed against the director of the Russian Academy of Science Library (BAN) over 54 rare books that have gone missing.
The prosecutor's office is alleging that the texts in question -- all made in France in the 18th and 19th centuries -- disappeared after being sent to France for evaluation.
It is alleged that the BAN director authorized the overseas transfer.
St Petersburg Channel 5 TV reported last Friday that some of the books have been seen in the French National Public Library in Paris.The BAN director was unavailable for comment last week.
Yakubovsky -- famous for his role in exposing a series of corruption scandals -- remains in St Petersburg's notorious Kresty prison awaiting trial.
Although three other men were arrested in Russia and 12 suspects detained in Israel, he is still the only person to have been charged in the theft.
Yakubovsky has been accused of complicity in the December 1994 heist after a driver and a bodyguard formerly in his employ testified against him.
They told police the Moscow-based lawyer ordered them to pick up a package at a St Petersburg apartment that contained the ancient manuscripts.