The club revealed on Tuesday that Marshall was present at the Precinct Hotel following the Rugby Match at AAMI Park.
St Kilda teammate Darragh Joyce was with Marshall, and was annoucned not to be joining his teammates ahead of their clash against West Coast in Perth after visiting the Rugby Test between Australia and France last week.
Marshall will now look to return to Victoria after travelling to Perth, while the rest of the St Kilda squad are allowed to continue in their preparations for their upcoming match.
“We’re grateful to the WA Government and Western Australian Police for permitting us to continue our training and we’ll continue to work with them over the coming days,” said Lethlean, per the club's statement.
“As we know, Rowan and Darragh’s situations are not unique and our thoughts are with everyone back in Victoria who currently is in lockdown.”
As reported by The Age's Daniel Cherny, Joyce had not made the venture to Western Australia after attending the AAMI Park match.
As a precautionary measure, St Kilda opted not to have Joyce fly interstate as his current exposure site tier was unknown at the time.
Meanwhile, Star Bulldog Josh Dunkley will be missing for the Dogs for at least a week after being forced to enter a 14-day quarantine.
Dunkley attended a local cafe on July 14, that cafe has since been revealed to be a tier 1 exposure site.
The Bulldogs said in a statement that Dunkley would only miss this weeks scheduled clash with Adelaide as his quarantine was backdated to July 14.
"Dunkley visited his local café on July 14, which was later declared an exposure site," the statement read.
"He was contacted yesterday by the Department of Health, and his mandatory quarantine period begins from the day he attended the site.
"Since July 14, Dunkley has received two separate negative coronavirus test results.
"The entire Bulldogs travelling party also received a negative result during their trip to the Gold Coast, as part of the AFL’s testing regime.
"Dunkley is complying with quarantine requirements and will be unavailable for this weekend’s Round 19 match, while the rest of the Bulldogs squad will continue their preparations as normal."