<?php

function add_dossier_to_person_page($content){

	if(! is_singular('persons')) return $content;

	$query = new WP_Query('post_type=cases');


	ob_start();

	?>
	<section id="person_dossier" class="cases-box">
		<div class="cases-box-header">
	    	<h1>Досье</h1>
	    	<hr>
		</div>
		<div class="cases-box-content">
			<?php

				while ( $query->have_posts() ) : $query->the_post();
					the_title();
					//get_template_part( '/templates/parts/content' );
				endwhile;
				wp_reset_postdata();
			?>

		</div>
	</section>

	<?php

	$content .= ob_get_contents();
	ob_get_clean();

	return $content;
}

add_filter('the_content', 'add_dossier_to_person_page', 20);