On January 1st 2014 the Palestinian ambassador to the Czech Republic died as he was settling into a new embassy building. It was soon determined that the ambassador was killed when he opened an old safe that was rigged with explosives. Normally, the explosives would only go off if the safe was forced open, to destroy what was inside and to hurt the intruders. When police (who cannot enter an embassy except for emergencies like this) arrived they found 12 firearms, which were seized as illegal. The Palestinians said they were legal and dated back to before the 1989 collapse of the communist governments in Eastern Europe. Upon further examination the police confirmed that the weapons did date back to the 1970s and 80s and that none show up in any Czech records as having been involved in criminal acts. The police suspect there are other questionable items in the embassy but diplomatic immunity limits how much they can search.
There was another problem. From 1918 to 1992 the present Czech Republic was half of Czechoslovakia. In 1992 Czechoslovakia was divided into separate the Czech and Slovak nations. That led to some chaos in national records and the loss of security officials to both of the new countries. The 1989 collapse of the communist government in Czechoslovakia also led to the disappearance of some records that could have explained what the Palestinians were up to. During the 1970s and 80s the communist governments of East Europe, on orders from the Soviet Union, provided training and other assistance for Palestinian and other Arab (and non-Arab) terrorist groups that were carrying out operations in the West. This was all unofficial and always denied by the Soviets. But after the Soviet Union collapsed in 1991 many Russians (and East Europeans) who worked in this terrorism support operation were willing to talk (often encouraged by a substantial fee).
The Palestinians established an embassy in Russia in 1974 and many more after that. Israel has long accused the Palestinians of using these embassies to support terrorist operations and to move weapons and explosives using shipments that have diplomatic immunity (from search by the host government).