diff --git a/docs/news.rst b/docs/news.rst
index 8cbfd00a0..15a405229 100644
--- a/docs/news.rst
+++ b/docs/news.rst
@@ -1,6 +1,14 @@
 Changelog
 =========
 
+next (unreleased)
+-----------------
+
+Lab
+^^^
+* Fix process group termination: always escalate to ``SIGKILL`` after ``SIGTERM``, since the previous ``poll()``-based check on the leader missed cases where a wrapper script exited cleanly while its children kept running (Travis Rivera Petit).
+
+
 v8.9 (2026-02-25)
 -----------------
 
diff --git a/lab/calls/call.py b/lab/calls/call.py
index 7c6e5cb2e..4491c240a 100644
--- a/lab/calls/call.py
+++ b/lab/calls/call.py
@@ -242,13 +242,33 @@ def _update_cpu_time(self):
 
     def _terminate_process_group(self):
         """Terminate the entire process group (parent and all children)."""
+        # Resolve the pgid once: after SIGTERM the leader may exit and be
+        # reaped, making a later os.getpgid(self.process.pid) fail even
+        # though children in the group are still running.
+        try:
+            pgid = os.getpgid(self.process.pid)
+        except (OSError, ProcessLookupError):
+            return
+
         with contextlib.suppress(OSError, ProcessLookupError):
-            os.killpg(os.getpgid(self.process.pid), signal.SIGTERM)
+            os.killpg(pgid, signal.SIGTERM)
+
         # Give it a moment to terminate gracefully.
         time.sleep(1)
-        if self.process.poll() is None:
-            with contextlib.suppress(OSError, ProcessLookupError):
-                os.killpg(os.getpgid(self.process.pid), signal.SIGKILL)
+
+        # We can't use self.process.poll() to decide whether to escalate:
+        # poll() only tracks the leader, but a wrapper leader (e.g.
+        # fast-downward.py) can exit cleanly after SIGTERM while its
+        # children (translate, search) keep running in the group. Probing
+        # the group with signal 0 tells us whether any member is still
+        # alive.
+        try:
+            os.killpg(pgid, 0)
+        except (OSError, ProcessLookupError):
+            return
+
+        with contextlib.suppress(OSError, ProcessLookupError):
+            os.killpg(pgid, signal.SIGKILL)
 
     def _monitor_time_limits(self):
         """