On Tuesday, 6 October officers arrested a 33-year-old man at Heathrow Airport, and a 28-year-old man at an address in Croydon.
They were arrested on suspicion of murder, causing grievous bodily harm, aggravated burglary and kidnap.
Both were taken to a south London police station where they remain in custody.
Police were called at 10.57pm on Thursday, 1 October to reports of a stabbing outside a block of flats on London Road in Morden.
Officers and the London Ambulance Service attended. Two men were found with stab wounds.
Despite the best efforts of paramedics, Patrick was pronounced dead at the scene at 11.26pm.
His next of kin have been made aware and are being support by specialist officers.
A second man, aged 33, was taken to hospital. His injuries were assessed as not life-threatening or life-changing.
Anyone with information is asked to call police on 101 quoting reference Cad 7953/01Oct.