Database schema:

CREATE TABLE incidents (
	case_number TEXT NOT NULL, 
	date DATE NOT NULL, 
	location TEXT NOT NULL, 
	subject_statuses TEXT NOT NULL, 
	subject_weapon TEXT NOT NULL, 
	subjects TEXT NOT NULL, 
	subject_count INTEGER NOT NULL, 
	officers TEXT NOT NULL, 
	PRIMARY KEY (case_number)
)


CREATE TABLE officers (
	case_number TEXT NOT NULL -- example: ['121982X', '44523A'],
	race TEXT -- example: ['L', 'W'],
	gender TEXT NOT NULL -- example: ['M', 'F'],
	last_name TEXT NOT NULL -- example: ['Fillingim', 'Patino'],
	first_name TEXT -- example: ['Brian', 'Michael'],
	full_name TEXT NOT NULL -- example: ['Fillingim, Brian', 'Patino, Michael'],
	CONSTRAINT fk_officers_incidents FOREIGN KEY(case_number) REFERENCES incidents (case_number)
)


CREATE TABLE subjects (
	case_number TEXT NOT NULL -- example: ['121982X', '44523A'],
	race TEXT NOT NULL -- example: ['L', 'B'],
	gender TEXT NOT NULL -- example: ['M', 'F'],
	last_name TEXT NOT NULL -- example: ['Curry', 'Chavez'],
	first_name TEXT -- example: ['Gabriel', 'James'],
	full_name TEXT NOT NULL -- example: ['Curry, James', 'Chavez, Gabriel'],
	CONSTRAINT fk_subjects_incidents FOREIGN KEY(case_number) REFERENCES incidents (case_number)
)

Question: What is the most common type of weapon that causes death?
Evidence: the most common type of weapon refers to max(count(subject_weapon)); causes death refers to subject_statuses = 'Deceased'

SQL:
SELECT subject_weapon FROM incidents WHERE subject_statuses = 'Deceased' GROUP BY subject_weapon ORDER BY COUNT(case_number) DESC LIMIT 1