This was the second arrest in a matter of days after the body of Mushfeeqa Hanslow, 18, was found in the lounge of her boyfriend’s flat in Hanover Park Avenue, Hanover Park on 27 February.
The teen had a gunshot wound to her head and a plastic bag and towel wrapped around it.
Police said her hands and feet were also tied with ropes.
Mushfeeqa had been alone inside the house with her boyfriend while his little brother played outside and his mother was at work.
Police said the latest arrest came after a “meticulous and intense two-day crime scene investigation” by Detective Sergeant Ashley Flink.
On 1 March, cops arrested the 19-year-old boyfriend.
He made a brief appearance at the Athlone Magistrates’ Court on Monday and is expected to be back in court on 9 March.
On the same day, cops arrested the second suspect in Surdown Walk, Hanover Park.
Police spokesperson, Captain Lance Goliath, says Flink and a team of crime scene investigators and experts took just two days to collect and analyse evidence that led to the arrests.
“Investigators revealed that a second suspect was on the run and a manhunt was launched and relevant roleplayers, such as informers and community-based organisations which are in partnership with police, were mobilised.
“On 5 March, Sergeant Flink made a second breakthrough when he arrested a 17-year-old male.”
Mushfeeqa’s mother, Ruwayda Adams, said: “I am happy the police made arrests and put the puzzle together.”