Someone here, can't remember who, told a story recently about how they locked their bike up in the same place every day while at work. The people at one of the near-by buildings never saw him coming or going, they just saw the same bike in the same place everyday, so one of them ended up taking it after wrongly assuming that it had been abandoned (he ended up getting it back). I wouldn't want to "liberate" a bike without knowing the whole story or having the go-ahead from someone with the authority to give the go-ahead.