It emerged on Tuesday that Mudryk tested positive for a banned substance after an “adverse finding in a routine urine test”.
Mudryk denies knowingly using any banned substance and has vowed to prove his innocence.
Asked if he believes Mudryk is innocent, Maresca said: “That is what we believe”
Mudryk has vowed to prove his innocence after an ‘adverse finding in a routine urine test’
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According to reports in Ukraine, Mudryk is still waiting for the result of a B sample.
But if the findings are confirmed then the 23-year-old Ukraine international could face a long ban.
Chelsea say they will work to establish what caused the test result.
Asked if Chelsea have any indication of a timeline of how long the process would take, Maresca said: “No, not yet.”
Addressing Mudryk's failed test for the first time, Maresca said on Wednesday: “Now the situation is a bit more clear. We have statement from the club, the club already said what we need to say. There is not anything to add apart from the club, the coaching staff and all the people inside the training ground, we trust and support Micha.
“We trust Micha. When these kind of things happen you need to support your player in all the aspects. We believe Micha, we trust Micha, we support Micha.
“Micha is a Chelsea player so it is my duty to be in contact with him. Me, the club, the players the team-mates are all there.”
Asked what he has said to Mudryk, Maresca said: “Just that we are all sad. We are there to support Micha. I spoke with him days ago.
“It is about any player in the world that this kind of thing happen to, they need support. No matter if he is 20 or 40, Italian or Ukrainian. When these kind of things happen, they need support.
“At the moment he can’t train. We are waiting. The club is there to support the player with all the things we need to support him in all aspects.”