queried posts but need to disable linking on certain ones

I have about 50 posts in one category… about 10 of them are also in another category.
I have them displayed in a grid of thumbnails.

I am looking to disable the thumbnail linking on only the 10… but am having a hard time finding a starting point. Here is what I have so far….

<?php $acs->query_posts(array('group_name' => 'People')); ?>
		<?php if ( have_posts() ) while ( have_posts() ) : the_post(); ?>

			<div class="grid-item">
			<a class="popup" href="<?php the_permalink(); ?>"><img src="<?php echo get_post_meta($post->ID, 'grid_thumbnail', true); ?>" /></a>
			</div>

		<?php endwhile; ?>

I feel like this might be an IF statement with the has_category function… but I don’t know where to start. Any help is appreciated.

Thanks.