FORT RECOVERY — The investigation continues into the death of a Mercer County man and his daughter.Mercer County Sheriff's Office deputies and BCI agents from the Attorney General's Office Special Investigation Unit asked for help Friday in the investigation into the deaths of Robert and Colleen Grube who were found on November 30 in rural Fort Recovery.The two were found dead inside Robert Grube's home. His daughter-in-law, Cassandra Grube, found them bound and shot. She told police she had gone to the house after family members were unable to contact of the two.Mercer County Sheriff Jeff Grey said Friday that investigators have narrowed the time of the incident to a possible two-hour window, but they are still asking the public to provide any information about suspicious activity on Nov. 29 and Nov. 30. It also appears that multiple perpetrators were present at the time, possibly a male and a female. A Toshiba laptop computer is missing from the home, but there were no signs of forced entry.“While we still don't know who committed this terrible crime, we have collected volumes of evidence that I believe will eventually lead us to the killers,” Grey said.Investigators have conducted more than 70 interviews, followed up on approximately 60 tips, requested the issuance of 46 court orders and subpoenas and served 11 search warrants, Grey said. Despite the progress, Grey would not predict when arrests might be made.“This case will not result in an arrest quickly, but I am confident that the case will be solved,” Grey said.The Sheriff's Office continues to ask anyone with any information to contact the Sheriff's Office through the tip line at 567-890-8477 or through the website at www.mercercountysheriff.org.You can comment on this story at www.LimaOhio.com.