Md. Code, Estates and Trusts § 4–104

If a testator is physically outside the State at the time the testator executes the will, the will is properly executed if it is:

(1) In writing;

(2) Signed by the testator or by some other person on the testator’s behalf, in the testator’s physical presence, and by the testator’s express direction; and

(3) Executed in conformity with:

(i) The provisions of § 4–102 of this subtitle;

(ii) The law of the domicile of the testator; or

(iii) The law of the place where the testator is physically located at the time the testator signs the will.