diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index b89cf19ebe6..22ad230ead9 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -540,6 +540,9 @@ Release 2.1.0-beta - UNRELEASED
 
     MAPREDUCE-5312. TestRMNMInfo is failing. (sandyr via tucu)
 
+    MAPREDUCE-5304. mapreduce.Job killTask/failTask/getTaskCompletionEvents 
+    methods have incompatible signature changes. (kkambatl via tucu)
+
 Release 2.0.5-alpha - 06/06/2013
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskCompletionEvent.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskCompletionEvent.java
index 96ab111a5c1..742da3f86a4 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskCompletionEvent.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskCompletionEvent.java
@@ -62,8 +62,9 @@ public class TaskCompletionEvent
     super(eventId, taskId, idWithinJob, isMap, org.apache.hadoop.mapreduce.
           TaskCompletionEvent.Status.valueOf(status.name()), taskTrackerHttp);
   }
-  
-  static TaskCompletionEvent downgrade(
+
+  @Private
+  public static TaskCompletionEvent downgrade(
     org.apache.hadoop.mapreduce.TaskCompletionEvent event) {
     return new TaskCompletionEvent(event.getEventId(),
       TaskAttemptID.downgrade(event.getTaskAttemptId()),event.idWithinJob(),
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/Job.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/Job.java
index 09eb8d5028e..78c6b4b1a9c 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/Job.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/Job.java
@@ -675,37 +675,57 @@ public class Job extends JobContextImpl implements JobContext {
    * Get events indicating completion (success/failure) of component tasks.
    *  
    * @param startFrom index to start fetching events from
-   * @return an array of {@link TaskCompletionEvent}s
+   * @return an array of {@link org.apache.hadoop.mapred.TaskCompletionEvent}s
    * @throws IOException
    */
-  public TaskCompletionEvent[] getTaskCompletionEvents(final int startFrom) 
-      throws IOException {
+  public org.apache.hadoop.mapred.TaskCompletionEvent[]
+    getTaskCompletionEvents(final int startFrom) throws IOException {
     try {
-      return getTaskCompletionEvents(startFrom, 10);
+      TaskCompletionEvent[] events = getTaskCompletionEvents(startFrom, 10);
+      org.apache.hadoop.mapred.TaskCompletionEvent[] retEvents =
+          new org.apache.hadoop.mapred.TaskCompletionEvent[events.length];
+      for (int i = 0; i < events.length; i++) {
+        retEvents[i] = org.apache.hadoop.mapred.TaskCompletionEvent.downgrade
+            (events[i]);
+      }
+      return retEvents;
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
   }
 
+  /**
+   * Kill indicated task attempt.
+   * @param taskId the id of the task to kill.
+   * @param shouldFail if <code>true</code> the task is failed and added
+   *                   to failed tasks list, otherwise it is just killed,
+   *                   w/o affecting job failure status.
+   */
+  @Private
+  public boolean killTask(final TaskAttemptID taskId,
+                          final boolean shouldFail) throws IOException {
+    ensureState(JobState.RUNNING);
+    try {
+      return ugi.doAs(new PrivilegedExceptionAction<Boolean>() {
+        public Boolean run() throws IOException, InterruptedException {
+          return cluster.getClient().killTask(taskId, shouldFail);
+        }
+      });
+    }
+    catch (InterruptedException ie) {
+      throw new IOException(ie);
+    }
+  }
+
   /**
    * Kill indicated task attempt.
    * 
    * @param taskId the id of the task to be terminated.
    * @throws IOException
    */
-  public boolean killTask(final TaskAttemptID taskId) 
+  public void killTask(final TaskAttemptID taskId)
       throws IOException {
-    ensureState(JobState.RUNNING);
-    try {
-      return ugi.doAs(new PrivilegedExceptionAction<Boolean>() {
-        public Boolean run() throws IOException, InterruptedException {
-          return cluster.getClient().killTask(taskId, false);
-        }
-      });
-    }
-    catch (InterruptedException ie) {
-      throw new IOException(ie);
-    }
+    killTask(taskId, false);
   }
 
   /**
@@ -714,20 +734,9 @@ public class Job extends JobContextImpl implements JobContext {
    * @param taskId the id of the task to be terminated.
    * @throws IOException
    */
-  public boolean failTask(final TaskAttemptID taskId) 
+  public void failTask(final TaskAttemptID taskId)
       throws IOException {
-    ensureState(JobState.RUNNING);
-    try {
-      return ugi.doAs(new PrivilegedExceptionAction<Boolean>() {
-        @Override
-        public Boolean run() throws IOException, InterruptedException {
-          return cluster.getClient().killTask(taskId, true);
-        }
-      });
-    }
-    catch (InterruptedException ie) {
-      throw new IOException(ie);
-    }
+    killTask(taskId, true);
   }
 
   /**
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/tools/CLI.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/tools/CLI.java
index 6de078d6467..37412e018d5 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/tools/CLI.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/tools/CLI.java
@@ -322,7 +322,7 @@ public class CLI extends Configured implements Tool {
         Job job = cluster.getJob(taskID.getJobID());
         if (job == null) {
           System.out.println("Could not find job " + jobid);
-        } else if (job.killTask(taskID)) {
+        } else if (job.killTask(taskID, false)) {
           System.out.println("Killed task " + taskid);
           exitCode = 0;
         } else {
@@ -334,7 +334,7 @@ public class CLI extends Configured implements Tool {
         Job job = cluster.getJob(taskID.getJobID());
         if (job == null) {
             System.out.println("Could not find job " + jobid);
-        } else if(job.failTask(taskID)) {
+        } else if(job.killTask(taskID, true)) {
           System.out.println("Killed task " + taskID + " by failing it");
           exitCode = 0;
         } else {