Nearly 28 years to the day after Virginia state trooper Johnny R. Bowman was slain in his Manassas home, law enforcement officials made a fresh appeal to the public for help in finally bringing the cold case to a close.

“We believe that someone can still provide a piece of the puzzle that will help solve this case,” said James W. McJunkin, assistant director of the FBI’s Washington field office.

The FBI, along with the Virginia State Police and Manassas City Police, announced Wednesday a new reward of $50,000.

“It is important for the public to know that no piece of information is too small to share,” McJunkin said.

Bowman was killed in his home in the Bristoe Station development in Manassas in the early morning of Aug. 19, 1984.

Around 4:15 a.m., the 31-year-old husband and father of one was awakened by the sound of the doorbell ringing. When he answered, he was attacked and stabbed more than 40 times.

“There was a lot of blood and overkill,” Special Agent Trudy Harris said in a 2004 interview. The killer “used [Bowman’s] body as a punching bag, except they were punching with a knife.”

Bowman’s wife, who was home at the time, called 911. Bowman, who had served with the Virginia State Police for 15 years, was taken to Prince William Hospital, where he died about 45 minutes later.

The attacker fled on foot, leaving behind a curly wig, a pair of nonprescription glasses and a construction hard hat.

Investigators followed leads to California and Ohio, and once said in a news conference that they believed another trooper was involved in the attack. In 2005, the Virginia State Police launched a campaign asking for the public’s help.

Forensic evidence, originally submitted to the FBI in 1984, was tested again in the late 1990s and again in 2010. Officials said the most recent DNA tests “identified new information,” but no arrests have been made.

Officials hope the $50,000 reward will persuade someone with information to come forward.

“I am confident that we are moving in the right direction with this investigation,” Manassas Police Chief Douglas W. Keen said. “It’s important for the public to understand that even after 28 years, we are committed to solving this murder and bringing the perpetrators to justice.”

Anyone with information can call the FBI at 800-CALL-FBI (800-225-5324) or the Virginia State Police at 703-803-2637.