His screen name was Libking Shooter Man and police say he offered to sell an iPhone on Facebook Marketplace.

But after meeting a 28-year-old buyer in St. Paul, he told him, “This is a stickup,” robbing him at gunpoint Thursday.

An investigation led police to determine “Libking Shooter Man” was Victor Issac Wion, 19, according to a criminal complaint filed Monday.

Two days after officer Jon Sherwood responded to the robbery report, he was on patrol and looking for Wion. Sherwood, who has been patrolling in St. Paul for 32 years, saw a parked car with a passenger who looked like Wion on Saturday, the complaint said.

Sherwood talked to the driver, whose 2-year-old child was in the back seat. The driver, 27, explained “he was negotiating a cellphone trade” with Wion, whom he knew as “Libking Shooter Man” on Facebook Marketplace, the complaint said.

Police arrested Wion, who had a BB gun and a felony amount of marijuana in his possession, according to the complaint charging him with first-degree aggravated robbery in the case from Thursday on Magnolia Avenue, near Hazelwood Street.

“Investigators are almost positive that Officer Sherwood interrupted a robbery about to take place, based on the history of the suspect,” said Sgt. Mike Ernster, a St. Paul police spokesman.

Wion, who was convicted of felony robbery and theft last year, faced years in prison, though judges sentenced him to months in the county workhouse instead.

Bruce Wenger, Wion’s attorney, said Wednesday that Wion “professes his innocence.”

St. Paul police have seen a spate of robberies occurring when people meet for purchases arranged online.

Last week, a permit-to-carry holder shot a man in the foot in the North End when he robbed him after they arranged via Facebook to meet for an iPhone purchase, according to a criminal complaint. The 18-year-old who was wounded was charged with robbery.

ROBBERY, THEFT, DRUG CASES FROM LAST YEAR

In January 2017, Wion pleaded guilty to robbing a taxi driver at gunpoint in St. Paul. In exchange, the Ramsey County attorney’s office dropped a separate robbery charge involving a carjacking in Maplewood.

Prosecutors agreed to the deal because Wion had a clean criminal record, he was pleading guilty to the more serious of the two charges and was ordered to pay restitution in both cases, said Dennis Gerhardstein, Ramsey County attorney’s office spokesman.

Wion told the court at that time “he needed to attend a meeting regarding his citizenship or he would miss the chance at becoming a United States citizen,” according to the complaint in the current case.

Wion was conditionally released from jail and sentencing was scheduling for two months away. But he was arrested again after a fight broke out at the Conway Recreation Center three days later.

Wion “used the confusion caused by the fight to steal (cell)phones” and was charged with felony theft, the complaint said.

Last April, a Ramsey County District Judge Richard Kyle Jr. sentenced Wion in the cabdriver robbery to nearly five years in prison, which he set aside for 15 years on conditions, including that Wion not get in trouble again.

Kyle ordered him to serve a year in the workhouse, with credit for 134 days served, and put him on supervised probation for 15 years.

The sentence was a downward departure from state sentencing guidelines. A typical sentence would have been four years in prison, Gerhardstein said.

Prosecutors agreed to a sentencing departure in January 2017, but later objected. Kyle’s sentence came “despite the fact that Wion had violated the plea agreement by failing to remain law-abiding, made misrepresentations about his citizenship meeting to the court,” according to the current criminal complaint by the county attorney’s office.

Kyle was out of the office Tuesday. Ramsey County Chief District Judge John Guthmann didn’t know particulars of the Wion case, though he said, “It’s a misnomer to say that a departure isn’t consistent with the (sentencing) guidelines because the guidelines tell judges how to do departures.”

Judges hear arguments from the prosecutor and defense attorney, and then consider factors including a defendant’s age, prior criminal record, whether they show remorse and whether they cooperated with authorities, Guthmann said.

If Wion is convicted of the new robbery charge, “he is in danger of jeopardizing his downward dispositional departure” from last year and being sent to prison in that case, said Wenger, his attorney.

It was unknown what type of citizenship meeting Wion was referring to last year. A U.S. Citizen and Immigration Services spokeswoman said she couldn’t discuss specific cases.

People found guilty of aggravated felonies are not eligible to become U.S. citizens.

About a week and a half after Wion initially was released from the workhouse last year, he was found with about 1 gram of cocaine in St. Paul, according to a criminal complaint. He pleaded guilty to felony drug possession and is awaiting sentencing.