ST. LOUIS—The final suspect has been arrested in connection with the killing of 19-year-old Jaylin Johnson near the Pagedale MetroLink station on July 7. 

The St. Louis County Prosecuting Attorney says Demetrious Strother, 19, is charged with murder and robbery. Police say he was with Steven Marion, 32, Kenneth Hall, 28, and Darnesha Thomas-Perry, 18, the night of the shooting. A juvenile suspect is also in custody.

The arrest came after the Major Case Squad released images of persons of interest resulting in numerous tips. 

Police say the Jaylin Johnson, a west St. Louis County resident who recently attended Marquette High School, was found dead after going to downtown St. Louis to meet with someone unknown people. 

Detectives say surveillance video from a MetroLink train shows the defendant and a group on the train making a plan and pointing at Johnson, who was speaking with two females who were with the group. 

The group, along with Johnson, exited at the Rock Road station in Pagedale. Police say Johnson was shot and killed near the MetroLink station and his belongings, including a cellphone and firearm, were taken. 

Investigators say the defendant and others then boarded an eastbound MetroLink train, leaving the victim behind.

The suspected shooter is seen on video holding the victim's firearm on the MetroLink train after the shooting. Another defendant is seen on the train unloading a firearm magazine and giving ammunition to another defendant.

“This is an ongoing investigation, and we intend to charge all of the individuals who participated in this callous robbery and heartless murder,” said St. Louis County Prosecuting Attorney Wesley Bell.