Peker was born in Sakarya, Turkey. He spent considerable time in Germany. He is a noted Turanist.
Peker was tried for the murder of the drug smuggler Abdullah Topçu, but acquitted. The two other defendants in the same case, considered to be Peker's employees, were sentenced to lifelong imprisonment.
After this, he fled to Romania and was sought for, amongst others, protection racketeering, coercion, and incitement to murder. During this time it was reported that he had been visited by a minister and a member of parliament from the Motherland Party and guaranteed, in return for an unknown favor, to be only imprisoned for a short period of time.
On August 17th, 1998; Peker was brought to Turkey of his own free will and surrendered to the authorities. The case against him was opened in September 1998. He pleaded guilty to the crimes for which he was accused and was found guilty of building a criminal organization. During the trial, Peker made some interesting remarks, which he never cleared up: "An older member of parliament sent me an SMS which said I shouldn't behave too arrogantly. I would like to tell you (the court) everything, because if I don't it could come to pass that I commit suicide under suspicious circumstances." The Prosecutors requested at least 7.5 years imprisonment, but Peker was only sentenced to eight months and 29 days and was released on May 14th, 1999.
On May 12th, 2005 he was arrested during Operation Butterfly. On January 31st, 2007 he was found guilty of building and leading a criminal organization, robbery, forgery, and two counts of false imprisonment, and sentenced to 14 years 5 months.
Peker is allegedly a member of the underground Turkish organization Ergenekon Veli Küçük said in 2008 that Peker was the "son of a friend." On August 5th, 2013 Peker was sentenced to ten years in prison as part of the Ergenekon trials however, he and the other convicts were released a few months later.
On January 13th, 2016 he said in a well-attended speech that the academics who signed the petition for peace will be massacred: “We will let your blood in streams and we will take a shower in your blood.”
On May 30th 2008; during his incarceration, Peker married his lawyer, Özge Yılmaz.