Martinez said he and his wife were walking down the street when he saw a man wearing an orange jumpsuit fleeing from a deputy, WRAL reported.
"It was like someone in a costume," Martinez told the television station Tuesday. "I saw that he had a handcuff on one hand and it was dangling around – both of his hands were free."
Martinez began chasing Knisley and tackled him.
"I took him down to the ground, pinned his arms around his back," Martinez told WRAL. "He begged me to let me go. [He] said, 'Let me go. Let me go. I am wanted for murder,' and I was like, 'There is no chance.'"
Another man helped Martinez secure the handcuff on Knisley and waited for deputies to arrive, the television station reported.
"We gave each other a fist punch, said good job and went to lunch," Martinez told WRAL.
Knisely is being held without bond in the Wake County Jail on a fugitive extradition warrant from Virginia.