An Interior Troops officer serving a 15-year sentence on charges of killing three civilians during the Chechen conflict will seek a retrial after a polygraph test indicated his innocence, his lawyer Dmitry Agranovsky said.

Former Colonel Sergei Arakcheyev and fellow officer Sergei Khudyakov were convicted in 2007 of robbing and killing three construction workers in Chechnya in 2003. They pleaded not guilty and were cleared twice in jury trials before being found guilty by a military court. Khudyakov, who was sentenced to 17 years, went into hiding after the trial.

Arakcheyev's planned appeal threatens to fuel tensions already on the rise after another Chechen war veteran, former Colonel Yury Budanov, was shot dead in Moscow last week.

The situation is further aggravated by reports that Chechen officials, whose ranks include many pardoned insurgents, are seeking personal data on war veterans, purportedly to investigate them over war crimes.

Arakcheyev's defense team gave him the polygraph test earlier this month at the prison in the Ryazan region where he is serving his sentence, Agranovsky told reporters Wednesday. Video snippets of the four-hour test, conducted by psychologist Oleg Baryshev, were posted on YouTube.

Arakcheyev's reactions during the test show he is telling the truth in denying any role in the triple killing, writer Marina Yudenich reported on her blog, citing a statement by Baryshev.

"We have received another weighty piece of evidence confirming his innocence," Yudenich said.

Arakcheyev, 30, also recorded a video appeal to Prime Minister Vladimir Putin. "I didn't kill. I have no blood on my hands," he said. "I never waged war on the Chechen nation, for which I have but the deepest respect. And I am sure the Chechen nation does not need me as a ritual sacrifice."

Arakcheyev released a similar plea to President Dmitry Medvedev in 2009 but received no reply.

The video of the polygraph was uploaded on YouTube on June 10, the same day that Budanov was gunned in downtown Moscow. Budanov, who commanded a tank division in Chechnya, was convicted of killing a Chechen girl but was released early on parole in 2009. Budanov's killer has not been identified.

Another Chechen war veteran was shot and wounded on Moscow's Komsomolskaya Ploshchad on Wednesday, media reports said, without identifying the victim.

Chechen officials acknowledged earlier this week that they were collecting information on soldiers who served in Chechnya in order to charge suspected war criminals. No such cases have been opened.

Many Chechens who fought federal forces in Chechnya have been pardoned and now occupy senior positions in the local government. No pardons have been extended to military or law enforcement officers.

This angers Alexander Perenzhiyev, a retired officer and member of the Association of Military Political Experts, who said the federal government was treating its own soldiers unfairly.

"It turns out that Russian soldiers are being prosecuted while many former rebel commanders have been amnestied and now even work as police," Perenzhiyev said by telephone Thursday.