(CNN) -- The explosive found hidden in a package on a plane in the United Arab Emirates on Friday may have traveled on passenger planes to get there, airline officials said Sunday. 

The explosive, along with a similar device found in the United Kingdom, appear to have been designed to detonate on their own, without someone having to set them off, the top White House counterterrorism official told CNN. 

"It is my understanding that these devices did not need somebody to detonate them," said John Brennan, President Barack Obama's assistant for homeland security and counterterrorism. 

U.S. investigators believe al Qaeda bomb maker Ibrahim Hassan al-Asiri, 28, is linked to that package and another one found on a second airplane in Britain's East Midlands Airport on Friday, a federal official, who was briefed by authorities, told CNN Sunday. Both packages were addressed to synagogues in Chicago, Illinois. 

Al-Asiri, who is thought to be in Yemen, is a Saudi who was high on Saudi Arabia's list of most wanted published in February 2009. He is also believed to be the bomber who designed last year's failed Christmas Day underwear bomb. 

Separately, an engineering student arrested in Yemen was released Sunday, along with her mother, according to her father, Mohammed Al-Samawi. She was earlier identified as Hanan Al-Samawi, a fifth-year student at Sanaa University in the Yemeni capital, said Abdul-Rahman Barman, a human rights attorney and activist who said he was asked to represent her. 

A high-level source in the United Arab Emirates said Hanan Al-Samawi's name was found on the cargo manifest of the device found in Dubai. 
which other bomb had Hassan designed?
 He is also believed to be the bomber who designed last year's failed Christmas Day underwear bomb. 