Washington ( CNN ) -- Additional details surfaced Thursday pointing to similarities between the bombs found in packages mailed from Yemen last week and a failed attempt to blow up a plane as it landed in Detroit , Michigan , last year . Investigators have found syringes associated with the explosives found last week , a U.S. official said . FBI agents investigating the failed attack on the plane landing in Detroit on December 25 found what appeared to be the remnants of a syringe . They made the discovery near the seat of Umar Farouk AbdulMutallab , a 25-year-old Nigerian citizen who faces charges including attempted murder . Investigators say he tried to blow up a plane with an explosive that was partly sewn into his underwear . Experts have said that the bomber probably used a liquid in a syringe with a chemical he was carrying ; that would have created a fire and ignited the explosives . It is the latest connection to be found between both incidents . PETN , a powerful explosive , was used in the parcel bomb plot and last year 's foiled bombing . And officials believe that al Qaeda in the Arabian Peninsula was responsible for both plots . `` This was AQAP , '' the U.S. official said Thursday . `` The body of information that people have reviewed over the past several days points very directly to AQAP . `` AQAP has shown a strong interest , and regrettably skill , in dealing with PETN , but that would n't be the only reason why this government would reach the conclusion that they are responsible . There is other information , too . '' Homeland Security Secretary Janet Napolitano recently said the two devices found on freight planes in the United Arab Emirates and the United Kingdom last week have `` all the hallmarks '' of a plot by al Qaeda in the Arabian Peninsula , the Yemen-based arm of the terrorist network . The same group also claimed responsibility for the December bombing attempt . The most recent security threat came to light Friday , when authorities in the United Arab Emirates and Britain found two packages sent from Yemen with explosives that were addressed to synagogues in Chicago , Illinois . The devices were packed in computer printer toner cartridges and designed to be detonated by a cell phone , a source close to the investigation said . The detonating substance was lead azide , a `` very powerful initiator '' that is easily prepared and is a standard substance in detonations , a source closely involved in the investigation said . The U.S. official said that testing on the devices is ongoing , but the assumption at this point is that the lead azide in the syringe was supposed to be an improvised blasting cap . When the circuit was completed , a wire in the syringe would heat up and ignite the lead azide , the official said . That would set off the PETN . One of the parcel bombs was disarmed minutes before it was due to explode , French Interior Minister Brice Hortefeux told French TV on Thursday in Paris . `` One parcel has been defused , one of the parcel bombs , was defused only 17 minutes before the time of the blast , '' Hotefeux said on France 2 . The White House and other U.S. officials are not confirming the French minister 's assertion . Robert Gibbs , the White House press secretary , said Thursday that Britain and UAE investigators have the packages . `` The investigators are looking into all features of the investigation , '' Gibbs said . `` Obviously , since those were to be loaded on U.S. carriers , the FBI is deeply involved . `` The forensics are very tedious , meticulous . ... We have confidence in that investigation , and when it 's concluded , we 'll look forward to that investigation being made public ... but I have no information to confirm that fact . '' Investigators in Yemen say they suspect that Ibrahim Hasan al-Asiri , al Qaeda 's top bomb maker in the region , is behind the explosive devices sent in the parcels . U.S. authorities are said to be also looking at al-Asiri because PETN was used in the parcels and by the underwear bomber . CNN 's Jeanne Meserve , Jill Dougherty and Becky Brittain contributed to this report .
Al Qaeda 's Yemen wing is suspected in last year 's bomb attacks . Ties are drawn to the Christmas Day bombing attempt . Operations are being carried out in Britain and the United Arab Emirates .