How to make Timer stop upon Death?

Hello! I'm trying to make my timer to stop when the player dies. It's currently only counting, but nothing happens when I die.

The code:

 using UnityEngine;
 using System.Collections;
 
 public class Timer : MonoBehaviour {
 
     public GUIText timerTex; //Text for GUI    
     public float levelTimer = 0f; 
     public bool updateTimer = false; 
             
     void start()
     {
         updateTimer = true;
     }
 
     void End()
     {
         updateTimer = false;
     }
 
     void Update()         
     {         
         if (updateTimer == true) 
         {    
             levelTimer += Time.deltaTime;
             timerTex.text = levelTimer.ToString ();
         }
 
     } 
 
     void OnTrigger (Collision2D col) 
     {
         
         if(col.gameObject.tag == "Player")
         {        
             updateTimer = false;
         } 
     }
 }

Please help! :)