The photomontage representing bin Laden was distributed in 2010 and published on the FBI web site, which later removed it at the politician's request.
Llamazares, who received a letter of apology from FBI representatives at the US Embassy in Spain shortly after the incident, said Tuesday that the bureau "has not corrected the situation at all" but only offered "a tiny apology".
In a statement on Cadena SER radio, the lawmaker recalled that his photo was used not only to recreate a likeness of bin Laden, but also of Atiyah Abd Al-Rahman, whom the CIA killed in August.
Osama was slain in May in the city of Abbottabad, Pakistan, during an operation by US Navy SEALs.
Llamazares noted that the two people represented in the photos made with parts of the lawmaker's face "have been killed".
United Left sources have said that since 2010 the politician has contacted several US law firms to file suit against the FBI.
In fact the case was accepted by one law office, but a few months later the US attorneys refused to proceed with the suit without ever saying why.
Llamazares has found a Spanish attorney's office to take over the case.
