A German engineer claimed to be held by al Qaeda militants was stabbed to death Thursday in the midst of a Nigerian military raid on a home in the northern city of Kano.

Edgar Raupach was abducted from a construction site in Kano in January. Soon an al Qaeda-affiliated cell, known to be active in parts of North Africa but not in Nigeria, released a statement, claiming it had captured Raupach, and released a video of him pleading for help.

The abductors demanded the release of a German woman, Filiz Gelowicz, convicted last year of aiding a foreign terrorist network, in exchange for Raupach's freedom. German officials released Gelowicz in April, after serving two-thirds of her sentence, but Raupach remained in captivity.

The Nigerian military operation sought to strike at the al Qaeda operatives, though officials reported that they were unaware of Raupach's presence at the site of the raid, and that a premature outbreak of gunfire between soldiers and militants escalated the situation beyond control.

On sighting the security forces, the terrorist element opened fire and threw (explosives), military spokesman Lt. Iweah Ikedichi said in a statement, the Associated Press reported. The security forces responded immediately, resulting in a gun battle that lasted for about 30 minutes.

Ikedichi added that five suspected al Qaeda militants were killed, and it was only after the fighting ceased that Raupach was found dead in the house.

Terrorist Activity Proliferating In Unstable Nigerian Regions

Raupach's murder comes as Nigerian authorities reported that another engineer of Italian nationality had been kidnapped in Nigeria's western state of Kwara by unidentified gunmen.

Although kidnappings have been rare so far Nigeria's west, foreign expatriates have increasingly been targeted by Islamic militants in the country's restive northern regions, which have been destabilized by political conflict and socio-economic disparities, as well as religious and ethnic tensions. Foreign contract workers in Nigeria's oil industry have also been targeted for ransom in the south.

Terrorist activity has also increased in northern Nigeria, particularly with the rise in recent years of Boko Haram, a loosely organized militant Islamist sect whose attacks have been primarily focused on domestic targets, though members of the group claimed responsibility for the 2011 bombing of the U.N. headquarters in Abuja, which killed 23 people.

Instability in northern Nigeria has also allowed al Qaeda to spread into the country, which has led to speculation that it might collaborate with Boko Haram and expand the sect's largely domestic terrorist activities to an international level.

The U.S. State Department is currently debating whether or not to designate Boko Haram a foreign terrorist organization, but the Nigerian government opposes the proposal, saying it would hinder its ability to pursue a political solution with Boko Haram, which is considered by some analysts to be fueled as much by political and socio-economic factors as it is by ideology.

Read more on Boko Haram here.

While kidnappings and violent attacks in Nigeria are commonly attributed to terrorist groups like Boko Haram and al Qaeda, they are also known to be committed by secular criminal gangs under the guise of terrorism.