WARSAW, Poland (AP) — Polish prosecutors investigating the 2010 plane crash that killed President Lech Kaczynski and 95 others said Monday that they are seeking help from foreign laboratories in testing the evidence.
The prosecutors are investigating whether anyone contributed in any way to the crash near a military airport in Russia. Poland's ruling party head, Jaroslaw Kaczynski — who is the late president's twin brother— has suggested it resulted from an attack of some kind.
No evidence has emerged so far to support that theory.
The National Prosecutor's Office said a police laboratory in Madrid was "yet another" foreign institution that would assist in carrying out forensic tests. The office said in a statement that the Madrid lab will check samples from the TU-154 M presidential plane's wreckage for traces of explosives.
Rzeczpospolita daily newspaper reported in 2012 that traces of explosives were detected in the wreckage, a claim that prosecutors later denied.
Prosecutors did not identify any other labs outside Poland that are participating in the investigation.
The remains of the aircraft and its flight recorders remain in Russia, which says they are needed there for an ongoing probe.
A separate probe led by Polish Defense Minister Antoni Macierewicz is seeking evidence to back the assassination theory.
Commissions of aviation experts in Poland and in Russia concluded the crash resulted from mistakes made by the crew in conditions of poor visibility while approaching the rudimentary airport in Smolensk.
The plane crash while Kaczynski was leading a delegation to ceremonies near Smolensk in memory of some 22,000 Polish officers killed by Soviet secret security forces in 1940.
Prosecutors in Poland have brought negligence charges against two officers of the now-dissolved regiment that was responsible for flying top officials. They also say that two Russian flight controllers from Smolensk should be charged for allegedly giving the plane's crew poor guidance, but they have no legal power to bring the charges.