The Police in Delta State said they had recovered corpses of four of its officers allegedly killed by suspected militants on May 15.
The Police Public Relations Officer (PPRO) in the state, Andrew Aniamaka, confirmed the recovery on Thursday in Warri.
"The militants will be fished out, as investigation is ongoing on the matter," he told journalists.
The deceased policemen were allegedly killed by the militants along the Benin river.
The victims were identified as Aghoro (Commander), Sagay, Andrew and Mejer and their bodies were deposited at both Sapale General Hospital and Central Hospital, Warri.
Their vandalised boat was also taken to Abiugborodo community under the care of some soldiers.
A reliable source told the News Agency of Nigeria that the policemen were invited by the militants to come and collect money to pave way for them to carry out their bunkering.
They were said to have ventured into the journey at about 2:30 a.m. on that fateful day without a back- up patrol boat.
"Only one, Mr Ugbo, on board the boat, swam to safety with bullet wounds and is currently recuperating at an undisclosed hospital," the source said.
Reacting to reports that the police were on illegal patrol when they got killed, Mr. Aniamaka said:
"We expect sympathy and to commiserate with the institution that lost four of its men inside the deep.
"We do not deploy our men to go and be collecting money from militants. Whatever duty they were on, we are investigating the matter.
"I am reflecting on how insensitive and callous certain persons can be especially on issues relating to the police," he said.