diff --git a/circlean_fs/root_partition/opt/groomer/IN_PROGRESS b/circlean_fs/root_partition/opt/groomer/IN_PROGRESS
new file mode 100644
index 0000000..ca46e57
--- /dev/null
+++ b/circlean_fs/root_partition/opt/groomer/IN_PROGRESS
@@ -0,0 +1 @@
+NOTE: This file is copied to the destination key when CIRCLean starts, and deleted once it completes successfully. If you see this file on your destination key it means that the copying process was INTERRUPTED or an ERROR occurred. You should treat files on the source key and destination key with care, and consider repeating the sanitization process. If you think you have found a bug, please report it at https://github.com/CIRCL/Circlean.
diff --git a/circlean_fs/root_partition/opt/groomer/groomer.sh b/circlean_fs/root_partition/opt/groomer/groomer.sh
index ac24412..3014157 100755
--- a/circlean_fs/root_partition/opt/groomer/groomer.sh
+++ b/circlean_fs/root_partition/opt/groomer/groomer.sh
@@ -56,20 +56,20 @@ run_groomer() {
             echo "GROOMER: ${partition} mounted at /media/${SRC}"
 
             # Put the filenames from the current partition in a logfile
-            find "/media/${SRC}" -fls "${LOGS_DIR}/contents_partition_${partcount}.txt"
+            # find "/media/${SRC}" -fls "${LOGS_DIR}/contents_partition_${partcount}.txt"
 
             # Create a directory on ${DST} named PARTION_$PARTCOUNT
             local target_dir="/media/${DST}/FROM_PARTITION_${partcount}"
             mkdir -p "${target_dir}"
-            local logfile="${LOGS_DIR}/processing_log.txt"
+            # local logfile="${LOGS_DIR}/processing_log.txt"
 
             # Run the current partition through filecheck.py
-            echo "==== Starting processing of /media/${SRC} to ${target_dir}. ====" >> "${logfile}"
+            # echo "==== Starting processing of /media/${SRC} to ${target_dir}. ====" >> "${logfile}"
             filecheck.py --source /media/"${SRC}" --destination "${target_dir}" || true
-            echo "==== Done with /media/${SRC} to ${target_dir}. ====" >> "${logfile}"
+            # echo "==== Done with /media/${SRC} to ${target_dir}. ====" >> "${logfile}"
 
             # List destination files (recursively) for debugging
-            ls -lR "${target_dir}"
+            # ls -lR "${target_dir}"
         else
             # Previous command (mounting current partition) failed
             echo "GROOMER: Unable to mount ${partition} on /media/${SRC}"
@@ -78,7 +78,6 @@ run_groomer() {
     done
 }
 
-
 main() {
     set -eu  # exit when a line returns non-0 status, treat unset variables as errors
     trap clean EXIT TERM INT  # run clean when the script ends or is interrupted
diff --git a/circlean_fs/root_partition/opt/groomer/mount_dest.sh b/circlean_fs/root_partition/opt/groomer/mount_dest.sh
index c2e558a..08f8bf6 100755
--- a/circlean_fs/root_partition/opt/groomer/mount_dest.sh
+++ b/circlean_fs/root_partition/opt/groomer/mount_dest.sh
@@ -7,6 +7,7 @@ clean(){
             cp "${DEBUG_LOG}" "${DST_MNT}/groomer_debug_log.txt"
         fi
         echo "GROOMER: Cleaning up in mount_keys.sh."
+        rm -rf "/media/${DST}/IN_PROGRESS"*
         ${SYNC}  # Write anything in memory to disk
         # Unmount source and destination
         pumount "${SRC}"
@@ -50,7 +51,11 @@ mount_dest_partition() {
     fi
 }
 
-prepare_dest_partition() {
+copy_in_progress_file() {
+    cp "/opt/groomer/IN_PROGRESS" "/media/${DST}/IN_PROGRESS"
+}
+
+prepare_dest_key() {
     rm -rf "/media/${DST}/FROM_PARTITION_"*  # Remove any existing "FROM_PARTITION_" directories
     # Prepare temp dirs and make sure they're empty if they already exist
     mkdir -p "${TEMP}"
@@ -70,7 +75,8 @@ main() {
     check_source_exists
     check_dest_exists
     unmount_dest_if_mounted
-    mount_dest_partition
+    mount_dest_key
+    copy_in_progress_file
     prepare_dest_partition
     ./groomer.sh
 }