Security sources confirmed on Tuesday that Nigerian authorities arrested five men, including a foreigner from Mauritania, who are believed to have ties to Al-Qaeda’s north African branch and are involved with the kidnapping of a German national in January.

According to reports, four of the five suspects had been arrested during a raid on a store owned by a Mauritanian last week and the fifth detained in a different raid.

“Guns and a laptop were recovered in the store and the documents found in the computer, including an AQIM operation manual, showed that the suspects are linked to AQIM and were involved in the kidnap of the German engineer in January,” one of the sources said in describing the store raid.

Al-Qaeda in the Islamic Maghreb, AQIM, claimed responsibility for the kidnap of German engineer Edgar Raupach, who was abducted in Kano in January. The radical group said in a statement last week that they were willing to swap him for a jailed Muslim woman.

Nigeria has recently faced criticism over its failed bid to rescue an Italian and British hostage earlier this month. The hostages had been killed by their captors during the failed rescue op by combined British and Nigerian forces.