Forensic tests showing that Christopher Coleman’s wife and two sons were slain before the time he said he left home focused police attention squarely on him, sources say.

Coleman, 32, is being held without bail on charges of first-degree murder in the strangulation of the three, who were found dead May 5. He told detectives he left for a gym about 5:45 a.m.; he called police before 7 a.m., concerned that they did not answer the phone.

Police revealed that Sheri Coleman, 31, and sons Garett, 11, and Gavin, 9, were slain in their separate bedrooms on the second floor by someone who used a ligature, such as a cord. But detectives have been officially mum on details such as the time of death.

Investigators learned of critical evidence Tuesday that led to an apparently sudden filing of the charges in Monroe County Circuit Court. But Maj. Jeff Connor, commander of the Major Case Squad, would not specify whether it was something new or a result of tests coming back on evidence already in hand.

Sources close to the case say physical evidence, such as liver temperature testing, indicated the victims were dead within an early morning range before Christopher Coleman departed the house at 2854 Robert Avenue.

He resigned last week from the security force of televangelist Joyce Meyer, based in Jefferson County, after what her ministry called a “violation of moral conduct.”

Law enforcement sources have said that Coleman was having an affair with a Florida woman who was a longtime friend of his wife.

William Margulis, the defense attorney, said his client “maintains his innocence.” Neither Coleman nor his lawyers have addressed the report of the affair.

Meanwhile, the family of Sheri Coleman is planning a wrongful-death lawsuit against Christopher Coleman, a spokesman said Thursday.

Enrico J. Mirabelli, who is a Chicago lawyer and Sheri Coleman’s cousin, said the family is working with Belleville lawyer Jack Carey to try to block Coleman from access to various property associated with his marriage.

“The purpose and goal is to ensure there is no ill-gotten gain from the murder of Sheri, Garett and Gavin,” Mirabelli said.

In November, Sheri Coleman’s name was removed from the title of the house where they had lived since 2005, leaving only Christopher E. Coleman as owner, according to county records.

Dr. Michael Baden, a celebrity among forensic pathologists given his frequent TV appearances, confirmed Thursday that he has been called in as a consultant for the prosecution.

Baden, former chief medical examiner for New York City, told a reporter, “I can’t comment on any aspect of the case right now.” He is an author, frequent TV news show guest and host of the HBO series “Autopsy.” (If you want to be famous but don’t want to be a waiter-slash-actor, become a pathologist. I’m quite sure the defense will be hiring one that says almost the exact opposite of what the famous Dr. Baden will say at trial.)