I am not admitted in MD (only in CA), so I can only provide a sort of general response. In general, all defamation actions (slander is a type of defamation) require these elements :
(1) a false and defamatory statement concerning another;
(2) publication of the statement, without privilege, to a third party;
(3) fault on the part of the publisher, amounting at least to negligence, in ascertaining whether the statement is true or false; and
(4) special damages.
[Restatement 2d, Torts § 558]
Typically speaking, actual falsity and knowledge of the falsity of the statement are hard to prove, if there is any aspect that is true. Also, statements made that are merely "opinions" are protected. (For example, there's a difference between saying "I think that guy is a crook" and saying "that guy is a felon." In the first instance you may be stating an opinion, where the 2nd example, if false, could be defamatory.)
The 3rd issue to address is damages: it's often hard to show actual damages resulting from the publication. In your case, you'd have to show what damages you suffered as a result of the statements.
That said, if the statements made about you are false, you may have a civil case against the person making them, but you'd have to assess what monetary losses you suffered to determine if the case was worth pursuing. I'd suggest discussing this with local counsel.
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