Robert Gene Rembert Jr. was born on March 15, 1970, in Cleveland, Ohio. His father was Robert Gene Rembert Sr., but information about his mother remains unknown. Information about Rembert's early years is limited.
 

On December 23, 1997, a 27-year-old Cleveland bus driver named Robert Rembert got into an altercation with 24-year-old Dadren Lewis in a parking lot, resulting in Lewis being shot. During his trial, Rembert's attorneys persuaded the judge that the shooting was accidental.

In 1998, Rembert was convicted of manslaughter and sentenced to six years in prison. After his release in 2004, he returned to Cleveland, found employment as a truck driver, and struggled with alcohol abuse and financial instability. At the time of his later arrest, he faced significant financial and housing difficulties, often relying on relatives and friends for accommodation.

On September 21, 2015, police stopped Rembert at a truck service stop in Medina County, near Cleveland. He was driving an SUV belonging to 26-year-old Morgan Nietzel, who had been discovered shot to death in her Cleveland home the previous day. Additionally, the body of 52-year-old Jerry Rembert, Robert’s cousin who had been housing him, was found. Rembert confessed that he had argued with his cousin Jerry the previous evening, leading to the fatal shooting of both Jerry and Nietzel, a mutual friend. After committing the murders, Rembert took several items and Nietzel's car.

During the investigation, Rembert provided blood and saliva samples for DNA testing. These samples connected him to the murder of 31-year-old Kimberly Hall, who had been found beaten and raped on June 10 of the same year, and to an older case from May 1997 involving the murder of 47-year-old Rita May Payne in Cleveland.

Rembert accepted a plea deal, admitting to the murders and providing detailed accounts of each crime. He revealed that during the Payne murder, he was employed as a bus driver and had lured her into a public service restroom at the Cleveland bus station, where he killed her. Despite investigations of bus drivers and station workers, Rembert had remained undetected. Due to his truck driving job, which took him to various cities in Ohio and Pennsylvania, he was also investigated for the murders of several other women involved in prostitution, though no additional charges have been filed.

Based on the plea agreement, Rembert was convicted of four murders and, on October 16, 2018, was sentenced to life imprisonment with the possibility of parole after 30 years. During his sentencing, he expressed remorse and sought forgiveness from the victims' families.