A Norwegian engineer and his Russian wife have been found dead with gunshot wounds in their Astrakhan apartment, and two suspects have been detained, investigators said Wednesday.

Staale Helseth, 40, and his wife Svetlana, 23, were discovered dead Tuesday, Alexei Bessonov, acting head of Astrakhan regional branch of the Investigative Committee, said by telephone.

Helseth was shot in the chest, while his wife was shot in the head, he said.

The young woman's parents discovered the bodies Tuesday, arriving at the apartment after being unable to reach their daughter Monday, Bessonov said.

Bessonov said two suspects had been detained in connection with the deaths but declined further comment, citing the ongoing investigation.

Alexei Veretyokha, a colleague of Helseth's with the Norwegian company Aker Solutions, said robbery appeared to be an unlikely motive. "Everything in the apartment remained as it was. Cell phones, laptops -- no valuables were stolen," Veretyokha, who visited the apartment Tuesday and talked to police, said in a telephone interview.

Helseth was the lead engineer on a firefighting module being built in Astrakhan and intended for the giant Kashagan oil field in Kazakhstan. He moved to Kazakhstan from Astrakhan in March to work on the unit. It was unclear exactly why he was visiting Astrakhan when he and his wife died.

"Staale was not dealing with any financial things," Veretyokha said. "That's why it's shocking he was killed in such a professional way. He was a regular builder. To tell you the truth, this is terrifying."

A Norwegian Embassy official in Moscow said the embassy had offered its support to investigators and would dispatch a representative to Astrakhan.

Helseth and his wife are survived by their infant son, who was spending the weekend at his grandparents' house when the couple died.