Yes, you can use the pronouns/adjectives 'this or that' to refer to a person:  used to indicate a person, place, thing,

This is my brother.
That is my sister.
This person is my friend.
That policeman is very helpful.

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Different style manuals give different answers to the question, can the relative pronouns 'who and that' be used to refer to a person.

It becomes the writer's choice as to which relative pronoun to use.

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The Chicago Manual of Style recommends who for people; that for a person, animal, or thing. 

The Associated Press Stylebook recommends using who to refer to "human beings and to animals with a name"; using that to refer to "inanimate objects and to animals without a name." 

Garner’s Modern English Usage supports both who and that to refer to people. 

Microsoft Manual of Style takes an approach similar to Garner's, saying, "Although there is no linguistic basis for not using that to refer to people . . . it is considered more polite to use who instead of that in references to people.” 

The Gregg Reference Manual gives the most complex advice after noting that both who and that are used to refer to people. Gregg states: "Select who when the individual person or the individuality of a group is meant, that when a class or type is meant."

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CONCLUSION:  The writer or speaker may select either relative pronoun when referring to a person.

Hello Partap. When referring to a person you would use the word 'who'.

Examples:  She is the lady who lives next door.

                     She is the lady who I was telling you about.