MOSCOW, Russia (CNN) -- The head of a humanitarian agency in Chechnya and her husband were found dead early Tuesday, their bodies stuffed in the trunk of their car, a prosecutor's spokeswoman said.
Zarema Sadulayeva, leader of Chechnya's Save the Generation and her husband, Ali Dzhabrailov -- also a member of the non-governmental organization -- had worked for many years helping children physically disabled by the two bloody wars in the volatile Russian province, a colleague told CNN.
The couple, in their mid-30s, were apparently abducted Monday afternoon outside the non-governmental organization's office in downtown Grozny, according to Maryan Nalayeva, spokeswoman for the Investigation Committee of the Chechen Prosecutor's Office.
Witnesses said five men arrived at the office in a vehicle at about 2 p.m. on Monday, and told the couple to follow them in their car to an undisclosed location, Nalayeva said.
"Contrary to earlier reports, it was established that no force was applied to them -- they left the building voluntarily," she said.
Three of the men were dressed in civilian clothing and the other two wore camouflage, she said.
The couple was found dead the next day.
"Their bodies, with multiple gun shots, were found in the trunk of their own car parked in a suburb of [the Chechen capital] Grozny at 4a local [8p Monday ET]," according to Nalayeva.
The Save the Generation organization was involved in purely humanitarian issues and was not involved with any politics, according to Nalayeva.
The organization provides social aid to disabled Chechen children and works in close partnership with UNICEF, the United Nations Children's Fund.
"Their organization was actively involved in rehabilitating kids who were crippled by landmines," said Ekaterina Sokiryanskaya, a human rights activist who worked with the couple.
Save the Generation organized treatment for the wounded children in Russia and abroad, and got them prosthetic limbs, Sokiryanskaya said.
"They also helped orphaned children," she added.
A criminal case has been opened on charges of murder and illegal handling of weapons, Nalayeva said. A team of investigators and forensic experts from Moscow and Rostov-on-Don has already flown into Grozny assist in the investigation, Nalayeva said.
Chechen President Ramzan Kadyrov said he is deeply outraged by the killings, in remarks to Russian news agencies based in Grozny.
"I am shocked by what has occurred," Kadyrov said, according to Interfax news agency. "It is a cynical, inhumane and demonstrative killing. This is the killing of people who devoted themselves to helping people with limited capabilities. I see this as a challenge to society, an attempt to intimidate the people of Chechnya."
He called on law enforcement to "do everything possible to solve this crime and make those responsible for it accountable for their actions."
"I consider it a matter of honor to ensure that the law enforcement agencies promptly investigate this crime, detain the culprits and give them the harshest punishment envisioned by Russian legislation," Kadyrov said.
In similar circumstances, a prominent human rights activist, journalist and head of the Chechen branch of the Memorial human rights center Natalia Estemirova was kidnapped near her home in Grozny on July 15. Later in the day, Estemirova's body was found with multiple bullet wounds.
Estemirova was a very close personal friend of another slain journalist Anna Politkovskaya who for years had been writing about lawlessness and human rights abuses in Chechnya.
Politkovskaya was killed in an elevator of her apartment building on October 7, 2007. So far, neither of the high-profile crimes have been solved.