Question: who stated that there is an exchange of materials when two objects come into contact with each other
[{'answer': 'Dr. Edmond Locard', 'provenance': [{'wikipedia_id': '1722373', 'title': "Locard's exchange principle", 'start_paragraph_id': 1, 'start_character': 211, 'end_paragraph_id': 1, 'end_character': 228, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1722373', 'title': "Locard's exchange principle", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 483, 'bleu_score': 0.9757530668325981, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5766051508992312207}, 'section': 'Section::::Abstract.'}]}]