Etinosa was reportedly shot dead on November 8, 2019, at the residence of one Happy Ikpomwosa, estranged wife of Iroghama.
It was gathered that the police arrested Iroghama because he was said to have earlier threatened to deal with the deceased.
Police sources said the woman, a mother of four, abandoned her husband for the deceased and refused all pleas to return home.
The threat to the deceased was said to have been reported to a traditional ruler in their area.
Edo Police spokesman, DSP Chidi Nwabuzor, who confirmed the incident, said operatives of the Ogida Police Division rushed the deceased to the hospital but he was confirmed dead on arrival.
He said investigation would unravel the killers.