Here is the MD law that applies
Md. CRIMINAL LAW Code Ann. § 6-403 (2011)
§ 6-403. Wanton trespass on private property
(a) Prohibited -- Entering and crossing property. -- A person may not enter or cross over private property or board the boat or other marine vessel of another, after having been notified by the owner or the owner's agent not to do so, unless entering or crossing under a good faith claim of right or ownership.
(b) Prohibited -- Remaining on property. -- A person may not remain on private property including the boat or other marine vessel of another, after having been notified by the owner or the owner's agent not to do so.
(c) Penalty. -- A person who violates this section is guilty of a misdemeanor
and on conviction is subject to:
(1) for a first violation, imprisonment not exceeding 90 days or a fine not exceeding $ 500 or both;
(2) for a second violation occurring within 2 years after the first violation, imprisonment not exceeding 6 months or a fine not exceeding $ 1,000 or both; and
(3) for each subsequent violation occurring within 2 years after the preceding violation, imprisonment not exceeding 1 year or a fine not exceeding $ 2,500 or both.
(d) Construction of section. -- This section prohibits only wanton entry on private property.
(e) Applicability to housing projects. -- This section also applies to property that is used as a housing project and operated by a housing authority or State public body, as those terms are defined in Division II of the Housing and Community Development Article, if an authorized agent of the housing authority or State public body gives the required notice specified in subsection (a) or (b) of this section.
SO, based on what you provide, if the property owner has told you to not come back, you must abide by that or face possible trespass charges.
As for service of process? You do not need to be present for that, you can have the local sheriff serve charges...they do not need you for that.