Daniel Young, 30, was attacked in Kendor Gardens, Morden while on his way for the second day of a new job.
In the footage, Mr Young can be seen walking along Dorset Street as he approached the park, shortly after 08:00 GMT last Tuesday.
The Met said they have found "no clear motive or reason" for his murder.
Two men have been arrested and bailed over his killing.
Det Ch Insp Cliff Lyons said the attack "appears to be the senseless murder of a brilliant young man" and appealed for anybody who was in the area at time to contact police.
Mr Young, originally from Paignton in Devon, had just begun working at Coventry University's London Campus International.
In the footage, he can be seen wearing a suit and carrying his laptop and a bag over his shoulder.
Detectives are still investigating whether another stabbing that occurred nearby at 07:25 on the same day is connected to his murder.
However, a Scotland Yard spokesperson said the two attacks had "not been linked forensically or evidentially" yet.
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