diff --git a/beacon_node/http_api/src/attestation_performance.rs b/beacon_node/http_api/src/attestation_performance.rs
index 2b4543656..ca68d4d04 100644
--- a/beacon_node/http_api/src/attestation_performance.rs
+++ b/beacon_node/http_api/src/attestation_performance.rs
@@ -83,6 +83,10 @@ pub fn get_attestation_performance<T: BeaconChainTypes>(
     }
 
     // Either use the global validator set, or the specified index.
+    //
+    // Does no further validation of the indices, so in the event an index has not yet been
+    // activated or does not yet exist (according to the head state), it will return all fields as
+    // `false`.
     let index_range = if target.to_lowercase() == "global" {
         chain
             .with_head(|head| Ok((0..head.beacon_state.validators().len() as u64).collect()))
diff --git a/consensus/state_processing/src/per_epoch_processing/epoch_processing_summary.rs b/consensus/state_processing/src/per_epoch_processing/epoch_processing_summary.rs
index 5e15aa3e1..6eb2f9776 100644
--- a/consensus/state_processing/src/per_epoch_processing/epoch_processing_summary.rs
+++ b/consensus/state_processing/src/per_epoch_processing/epoch_processing_summary.rs
@@ -129,7 +129,12 @@ impl<T: EthSpec> EpochProcessingSummary<T> {
             EpochProcessingSummary::Altair {
                 participation_cache,
                 ..
-            } => participation_cache.is_current_epoch_timely_target_attester(val_index),
+            } => participation_cache
+                .is_current_epoch_timely_target_attester(val_index)
+                .or_else(|e| match e {
+                    ParticipationCacheError::InvalidValidatorIndex(_) => Ok(false),
+                    e => Err(e),
+                }),
         }
     }
 
@@ -222,7 +227,12 @@ impl<T: EthSpec> EpochProcessingSummary<T> {
             EpochProcessingSummary::Altair {
                 participation_cache,
                 ..
-            } => participation_cache.is_previous_epoch_timely_target_attester(val_index),
+            } => participation_cache
+                .is_previous_epoch_timely_target_attester(val_index)
+                .or_else(|e| match e {
+                    ParticipationCacheError::InvalidValidatorIndex(_) => Ok(false),
+                    e => Err(e),
+                }),
         }
     }
 
@@ -248,7 +258,12 @@ impl<T: EthSpec> EpochProcessingSummary<T> {
             EpochProcessingSummary::Altair {
                 participation_cache,
                 ..
-            } => participation_cache.is_previous_epoch_timely_head_attester(val_index),
+            } => participation_cache
+                .is_previous_epoch_timely_head_attester(val_index)
+                .or_else(|e| match e {
+                    ParticipationCacheError::InvalidValidatorIndex(_) => Ok(false),
+                    e => Err(e),
+                }),
         }
     }
 
@@ -274,7 +289,12 @@ impl<T: EthSpec> EpochProcessingSummary<T> {
             EpochProcessingSummary::Altair {
                 participation_cache,
                 ..
-            } => participation_cache.is_previous_epoch_timely_source_attester(val_index),
+            } => participation_cache
+                .is_previous_epoch_timely_source_attester(val_index)
+                .or_else(|e| match e {
+                    ParticipationCacheError::InvalidValidatorIndex(_) => Ok(false),
+                    e => Err(e),
+                }),
         }
     }