As preparations intensify for the memorial service of Charlie Kirk in Arizona, a security consultant and former NYPD detective advises mourners to stay vigilant.

“Pull your face out of your phone, put it in your pocket. Pay attention,” Pat Brosnan urged. 

The event, scheduled for this weekend at State Farm Stadium, anticipates drawing a massive crowd. Officials project over 100,000 people will congregate in and around the venue, with attendees filling the 63,000-seat stadium and additional overflow areas outside.

“From the moment you arrive… keep your eyes wides open… notice who’s to your right, who’s to your left, who’s behind you? Observe their actions,” Brosnan told Fox News Digital. “Be aware of your surroundings from all angles.”

Despite the full weight of federal and local security coordination, Brosnan was realistic about the limitations of modern threat detection.

“There are weapons that can bypass even the most advanced security systems today,” he noted. “The fact is, [such weapons] could make it inside.”

Which is why Brosnan says public vigilance is not optional — it’s essential.

More than just a technical or tactical issue, Brosnan says situational awareness is about shared responsibility.

“Anyone nearby who hears or sees something suspicious must report it instantly, without hesitation,” he emphasized.

Kirk leaves behind his wife, Erika Kirk, and their two young children. Erika, along with the president, vice president, and other dignitaries, is expected to speak at the service.

Kirk was fatally shot last week while addressing an event hosted by the Turning Point chapter at Utah Valley University in Orem, Utah.

The accused, 22-year-old Tyler Robinson, is currently in custody without bail and faces multiple charges, including murder.

Stepheny Price covers crime including missing persons, homicides and migrant crime. Story tips: stepheny.price@fox.com.