Last call at the Falls could happen soon now that authorities officially have a suspect in the murder of Imette St. Guillen, who was last seen leaving the SoHo bar around 4 a.m. on February 25.

A week ago, the New York State Liquor Authority and city prosecutors were eager to take action after word leaked that a bar manager had lied to detectives and that the bar had illegally employed a convicted felon. Sources say the New York Police Department asked them to back off – because police wanted more time to solve the murder before other agencies stepped in.

Now that the Brooklyn district attorney is officially targeting a Falls bouncer, Darryl Littlejohn, the bar and its owners could be back in the crosshairs.

At the very least, we know the Falls hired a bouncer whose rap sheet bars him from working in a bar. We also know Littlejohn did not have a state license to work in security. The bar will probably pay for those mistakes with its liquor license, which expires in July.

But the bar’s manager could be in additional trouble. Daniel Dorrian initially told detectives that St. Guillen left the Falls alone at closing time. Nearly a week later, though, Mr. Dorrian changed his story and said he asked Littlejohn to escort the young woman out. Mr. Dorrian also belatedly described hearing a commotion as the bouncer and the patron left.

That makes Mr. Dorrian a central witness in the case, identifying the suspect as the last person to be seen with St. Guillen before her body was discovered 11 miles away in Brooklyn 17 hours later.

Law enforcement officials are furious that Mr. Dorrian’s statements gave Littlejohn five days to destroy evidence. But the NYPD also worried that Mr. Dorrian might stop cooperating if prosecutors started punishing him or his family’s bar. Authorities were in unanimous agreement that solving the murder was more important than any ancillary action.

Now that police have DNA evidence supposedly linking Littlejohn to the wires used to bound St. Guillen’s hands and feet, Mr. Dorrian could be in trouble if prosecutors are determined to go after him.

At some point, legal experts say, Mr. Dorrian could seek immunity in exchange for continuing to cooperate with cops. He has already retained a lawyer with plenty of experience handling obstruction of justice charges – a former federal prosecutor in Manhattan, Daniel Gitner, who just last year convicted Lil’ Kim for interfering with a shooting investigation.

Mr. Dorrian is certainly lucky his inquisitors were city police and not FBI agents. As Martha Stewart taught us, lying to G-men is a crime. But lying to the NYPD is only a crime if Mr. Dorrian specifically intended to throw police off the killer’s trail. If he lied simply to protect himself or his bar from scrutiny – and had no idea his bouncer could be involved in a murder – Mr. Dorrian’s selfish behavior would qualify as despicable but not criminal.

Stewart goes to jail for an obscure stock trade, while a witness in a murder investigation could be free to change his story to the police while a killer roams free. Perhaps state lawmakers might want to take a look at this loophole.

Mr. Goldin’s column appears regularly in The New York Sun.