RICHMOND HEIGHTS, Mo. (KMOV.com) -- Police said the 23-year-old South City man who was killed after running away from a Richmond Heights officer near the Galleria Mall had his gun raised when the officer shot him on Saturday afternoon.

Sergeant Ben Granda with the St. Louis County Police said this all started when a security guard at the mall informed a Richmond Heights officer about an armed man, later identified as Terry Tillman, inside the mall around 3 p.m. Police said Tillman had entered a store in the mall with his handgun.

News 4 obtained court documents indicating Tillman had a criminal history. He was a convicted felon illegally in possession of a firearm. Tillman was carrying the weapon on him inside the Galleria, which is against the mall's policy. There are signs stating the mall is a gun-free zone all around the property.

The guard and officer approached Tillman to tell him about the Galleria's no guns policy but Tillman fled the area.

The Richmond Heights officer chased him on foot and reached the parking lot adjacent to Simmons Bank on Clayton Rd. and Clayshire Dr. in Clayton, across the street from the Galleria.

Police said the 50-year-old officer then shot Tillman while at the parking lot. The officer told police Tillman had his firearm raised at the time. Granda said the officer struck Tillman in the front and the autopsy shows Tillman did not suffer any injuries to the back. The officer discharged three to five shots as the autopsy is not conclusive yet, Granda said. Tillman did not discharge his firearm.

“The officer who discharged his firearm indicated that Mr. Tillman had his firearm raised at the time that he did. He discharged his firearm and struck Mr. Tillman in the torso," Granda said. He later added, "There are no incidents that come under greater scrutiny than a police officer-involved shooting."

Police provided an update on the officer-involved shooting on Tuesday. Click here to watch.

Tillman then fell and police took the handgun. Life-saving treatment was administered but Tillman was pronounced dead on the scene.

Police said there were at least 25 rounds in Tillman’s magazine. Granda said they are exploring how Tillman obtained his handgun and why it was in his possession as he is a convicted felon and isn’t allowed to own firearms.

It's 2019 ... any reasonable person who sees an extended magazine protruding from a person, especially in a law enforcement capacity, has an obligation to contact individuals and investigate," Sergeant Ben Granda with the St. Louis County Police said. "Look nationally ... see if we have any mass shootings ... There is no way we cannot address that person. Those signs are posted on every door going into that establishment. Mr. Tillman was contacted by those officers [and] I wish they would have explained the policy and he would have come back to do his shopping on another date when he was not armed.

The officer has 23 years of experience with the Richmond Heights Police Department.

In an update provided on Tuesday, Granda said investigators are looking at 158 surveillance cameras from the Galleria and other surveillance cameras from the bank adjacent to the parking lot where the shooting happened.

Granda said the department is calling more detectives to work on the case. He also said the department is looking for more witnesses.

A woman who says she's the sister of Tillman told News 4 her brother was at the mall shopping with his pregnant girlfriend. Rachel Jones said she doesn't understand what led to the shooting.

"Words can't explain that's my only brother, he had a baby [coming,]" Jones said.

Court records show he allegedly sold a stolen vehicle out of Ballwin to a Chicago resident. An arrest warrant was issued in February when he failed to appear in court in connection to the stolen vehicle claim. Other court documents show Tillman served five years out of a ten-year sentence for robbery and armed criminal action charges dating back to 2013.

Jones and other family members and friends held a vigil for Tillman on Sunday afternoon. Jones said Tillman's criminal history is irrelevant to his shooting death.

"That man didn’t know about a felony when he was chasing my brother," Jones said. "He ain’t know about his records, so what relevance is that, of you chasing him and shooting him down."

St. Louis County Prosecutor Wesley Bell promised transparency throughout the investigation.

"We take these things seriously and support our law enforcement and will be as transparent as possible but transparency doesn't always happen immediately," Bell said.

In tragic cases like these, it is important to understand that the need to inform the public has to be balanced with ensuring the integrity of the investigation," St. Louis County Prosecutor Wesley Bell said. "I am fully aware of how sensitive this issue is and I want to assure all residents a thorough and detailed investigation is being conducted. I ask for patience as this process unfolds and I will update the community as more information becomes available.

The St. Louis County Police Department’s Bureau of Crimes Against Persons Unit is investigation the situation.

Police believe there were additional witnesses near the scene. If you have any information, call 636-529-8210. To remain anonymous, call CrimeStoppers at 866-371-8477.