diff --git a/app/controllers/graders_controller.rb b/app/controllers/graders_controller.rb
--- a/app/controllers/graders_controller.rb
+++ b/app/controllers/graders_controller.rb
@@ -2,7 +2,7 @@
 
   before_filter :admin_authorization
 
-  verify :method => :post, :only => ['clear_all'], 
+  verify :method => :post, :only => ['clear_all', 'clear_terminated'], 
          :redirect_to => {:action => 'index'}
 
   def index
@@ -10,9 +10,10 @@
   end
 
   def list
-    @grader_processes = GraderProcess.find(:all, 
-                                           :order => 'updated_at desc')
+    @grader_processes = GraderProcess.find_running_graders
     @stalled_processes = GraderProcess.find_stalled_process
+
+    @terminated_processes = GraderProcess.find_terminated_graders
     
     @last_task = Task.find(:first,
                            :order => 'created_at DESC')
@@ -26,6 +27,13 @@
     redirect_to :action => 'list'
   end
 
+  def clear_terminated
+    GraderProcess.find_terminated_graders.each do |p|
+      p.destroy
+    end
+    redirect_to :action => 'list'
+  end
+
   def clear_all
     GraderProcess.find(:all).each do |p|
       p.destroy
diff --git a/app/models/grader_process.rb b/app/models/grader_process.rb
--- a/app/models/grader_process.rb
+++ b/app/models/grader_process.rb
@@ -15,18 +15,31 @@
       grader.active = nil
       grader.task_id = nil
       grader.task_type = nil
+      grader.terminated = false
       grader.save
     else
       grader = GraderProcess.create(:host => host, 
                                     :pid => pid, 
-                                    :mode => mode)
+                                    :mode => mode,
+                                    :terminated => false)
     end
     grader
   end
+ 
+  def self.find_running_graders
+    GraderProcess.find(:all,
+                       :conditions => {:terminated => 0})
+  end
 
-  def self.find_stalled_process()
+  def self.find_terminated_graders
     GraderProcess.find(:all,
-                       :conditions => ["active AND updated_at < ?",
+                       :conditions => "`terminated`")
+  end
+
+  def self.find_stalled_process
+    GraderProcess.find(:all,
+                       :conditions => ["(`terminated` = 0) AND active AND " + 
+                                       "(updated_at < ?)",
                                        Time.now.gmtime - GraderProcess.stalled_time])
   end
   
@@ -54,6 +67,11 @@
     self.save
   end                
 
+  def terminate
+    self.terminated = true
+    self.save
+  end
+
   protected
 
   def self.stalled_time()
diff --git a/app/views/graders/_grader_list.html.haml b/app/views/graders/_grader_list.html.haml
--- a/app/views/graders/_grader_list.html.haml
+++ b/app/views/graders/_grader_list.html.haml
@@ -1,18 +1,24 @@
+- if grader_list.length!=0
+  %table.graders
+    %tr
+      %th host
+      %th pid
+      %th mode
+      %th last updated
+      %th type
+      %th task
+    - grader_list.each do |grader|
+      - if grader.active
+        - c = 'active'
+      - else
+        - c = 'inactive'
+      %tr{:class => c}        
+        = render :partial => 'grader', :locals => {:grader => grader}
+        - if not grader.terminated
+          %td= link_to 'stop', {:action => 'stop', :id => grader}
+        - else
+          %td= link_to 'clear', {:action => 'clear', :id => grader}
+- else
+  %ul
+    %li None
 
-%table.graders
-  %tr
-    %th host
-    %th pid
-    %th mode
-    %th last updated
-    %th type
-    %th task
-  - grader_list.each do |grader|
-    - if grader.active
-      - c = 'active'
-    - else
-      - c = 'inactive'
-    %tr{:class => c}        
-      = render :partial => 'grader', :locals => {:grader => grader}
-      %td= link_to 'clear', {:action => 'clear', :id => grader}
-
diff --git a/app/views/graders/list.html.haml b/app/views/graders/list.html.haml
--- a/app/views/graders/list.html.haml
+++ b/app/views/graders/list.html.haml
@@ -18,10 +18,17 @@
   = link_to "#{@last_test_request.id}", :action => 'view', :id => @last_test_request.id, :type => 'TestRequest'
 
 
-%h3 Current graders
+%h2 Current graders
 
 = render :partial => 'grader_list', :locals => {:grader_list => @grader_processes}
 
-%h3 Stalled graders
+%h2 Stalled graders
 
 = render :partial => 'grader_list', :locals => {:grader_list => @stalled_processes}
+
+%h2 Terminated graders
+
+- form_for :clear, nil, :url => {:action => 'clear_terminated'} do |f|
+  = submit_tag 'Clear data for terminated graders'
+
+= render :partial => 'grader_list', :locals => {:grader_list => @terminated_processes}
diff --git a/db/schema.rb b/db/schema.rb
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -9,7 +9,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20090416235658) do
+ActiveRecord::Schema.define(:version => 20090426131044) do
 
   create_table "announcements", :force => true do |t|
     t.string   "author"
@@ -51,6 +51,7 @@
     t.datetime "updated_at"
     t.integer  "task_id"
     t.string   "task_type"
+    t.boolean  "terminated"
   end
 
   add_index "grader_processes", ["host", "pid"], :name => "index_grader_processes_on_ip_and_pid"