Moscow - Fellow passengers thought nothing of it when Alexei W, 23, invited them to share a drink and toast with him "on the birth of his little daughter."
Yet the brandy offered so generously was laced with powerful tranquillizers, and the friendly young man robbed his victims as they lost consciousness and lay dying in Moscow commuter trains.
On Thursday, Russian police appealed to the public for more information, after arresting a serial killer suspected of having murdered at least 13 people and injured another 12, some of them seriously, over a period of three years.
When the young man was arrested in the capital on Wednesday, he tried to hide the drugs he used in his underwear, media reports said.
A search of the 23-year-old's flat after his arrest turned up numerous wallets, credit cards, passports and mobile phones, prompting police to suspect that the number of Alexei W.'s victims could be significantly higher.
Equally, police said, similar cases of attacks had occurred on other rail lines.
According to police, the suspect had arrived in Moscow from Vladivostok in eastern Russia, where he had previously been imprisoned for theft.
On Thursday, footage of the suspected killer was shown on the Russian internet portal lifenews.ru: a well dressed young man who laughs in response to questions posed by Russian journalists. "What do you want?", he says, seemingly without emotion.
Alexei W. used to single out apparently well-off men who seemed to be on their way home from parties and in high spirits, police officer Tatjana Morosova was quoted as saying by the Russian newspaper Komsomolskaya Pravda.
When invited to share a drink with him, most of the victims readily agreed. The young man had used medication intended for the treatment of strongly psychotic patients, police said. He often left his victims to die in icy cold winter temperatures.
Many victims were still in a coma; Others would have to be treated for neurological damage or memory loss for years, according to police reports.
Investigating the killings had taken years, police said. The suspect was finally tracked down after one victim survived the attack.
Because he was ill, the elderly man had only taken a small sip of the lethal cocktail out of politeness. He regained consciousness and helped produce the composite photograph that led to the suspect's arrest.//dpa
