diff --git a/include/iGenVar.hpp b/include/iGenVar.hpp
index c5d1352d..e1420726 100644
--- a/include/iGenVar.hpp
+++ b/include/iGenVar.hpp
@@ -11,6 +11,7 @@ struct cmd_arguments
 // Input:
     /* -i */ std::filesystem::path alignment_short_reads_file_path{""};
     /* -j */ std::filesystem::path alignment_long_reads_file_path{""};
+    /* -g */ std::filesystem::path genome_file_path{""};
 // Output:
     /* -o */ std::filesystem::path output_file_path{};
     /* -s */ std::string vcf_sample_name{"MYSAMPLE"};
diff --git a/include/variant_detection/snp_indel_detection.hpp b/include/variant_detection/snp_indel_detection.hpp
new file mode 100644
index 00000000..c1ddbd10
--- /dev/null
+++ b/include/variant_detection/snp_indel_detection.hpp
@@ -0,0 +1,9 @@
+#pragma once
+
+#include <seqan3/std/filesystem>
+
+/*!
+ * \brief Detect Single Nucleotide Polymorphisms (SNPs) and short deletions and insertions.
+ * \param reads_filename The file path where to find the sequenced reads.
+ */
+void detect_snp_and_indel(std::filesystem::path const & reads_filename);
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8701a396..be351ffd 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -11,6 +11,7 @@ add_library ("${PROJECT_NAME}_lib" STATIC modules/clustering/hierarchical_cluste
                                           structures/cluster.cpp
                                           structures/junction.cpp
                                           variant_detection/method_enums.cpp
+                                          variant_detection/snp_indel_detection.cpp
                                           variant_detection/variant_detection.cpp
                                           variant_detection/variant_output.cpp)
 
diff --git a/src/iGenVar.cpp b/src/iGenVar.cpp
index a434f624..017d1056 100644
--- a/src/iGenVar.cpp
+++ b/src/iGenVar.cpp
@@ -8,6 +8,7 @@
 #include "modules/clustering/hierarchical_clustering_method.hpp"    // for the hierarchical clustering method
 #include "modules/clustering/simple_clustering_method.hpp"          // for the simple clustering method
 #include "structures/cluster.hpp"                                   // for class Cluster
+#include "variant_detection/snp_indel_detection.hpp"                // for detect_snp_and_indel
 #include "variant_detection/variant_detection.hpp"                  // for detect_junctions_in_long_reads_sam_file()
 #include "variant_detection/variant_output.hpp"                     // for find_and_output_variants()
 
@@ -35,6 +36,11 @@ void initialize_argument_parser(seqan3::argument_parser & parser, cmd_arguments
                       "Input long read alignments in SAM or BAM format (PacBio, Oxford Nanopore, ...).",
                       seqan3::option_spec::standard,
                       seqan3::input_file_validator{{"sam", "bam"}} );
+    parser.add_option(args.genome_file_path,
+                      'g', "input_genome",
+                      "Input the reference genome in FASTA or FASTQ format.",
+                      seqan3::option_spec::standard,
+                      seqan3::input_file_validator{{"fasta", "fa", "fastq"}} );
     parser.add_option(args.output_file_path, 'o', "output",
                       "The path of the vcf output file. If no path is given, will output to standard output.",
                       seqan3::option_spec::standard,
@@ -124,18 +130,26 @@ void detect_variants_in_alignment_file(cmd_arguments const & args)
     std::vector<Junction> junctions{};
     std::map<std::string, int32_t> references_lengths{};
 
-    // short reads
-    if (args.alignment_short_reads_file_path != "")
+    if (args.genome_file_path.empty())
     {
-        seqan3::debug_stream << "Detect junctions in short reads...\n";
-        detect_junctions_in_short_reads_sam_file(junctions, references_lengths, args);
-    }
+        // short reads
+        if (!args.alignment_short_reads_file_path.empty())
+        {
+            seqan3::debug_stream << "Detect junctions in short reads...\n";
+            detect_junctions_in_short_reads_sam_file(junctions, references_lengths, args);
+        }
 
-    // long reads
-    if (args.alignment_long_reads_file_path != "")
+        // long reads
+        if (!args.alignment_long_reads_file_path.empty())
+        {
+            seqan3::debug_stream << "Detect junctions in long reads...\n";
+            detect_junctions_in_long_reads_sam_file(junctions, references_lengths, args);
+        }
+    }
+    else
     {
-        seqan3::debug_stream << "Detect junctions in long reads...\n";
-        detect_junctions_in_long_reads_sam_file(junctions, references_lengths, args);
+        seqan3::debug_stream << "Detect SNPs, insertions and deletions in short reads...\n";
+        detect_snp_and_indel(args.alignment_long_reads_file_path);
     }
 
     std::sort(junctions.begin(), junctions.end());
@@ -233,6 +247,9 @@ int main(int argc, char ** argv)
         return -1;
     }
 
+    // Set the number of decompression threads
+    seqan3::contrib::bgzf_thread_count = args.threads;
+
     // Check that method selection contains no duplicates.
     std::vector<detection_methods> unique_methods{args.methods};
     std::ranges::sort(unique_methods);
diff --git a/src/variant_detection/snp_indel_detection.cpp b/src/variant_detection/snp_indel_detection.cpp
new file mode 100644
index 00000000..3d7ece99
--- /dev/null
+++ b/src/variant_detection/snp_indel_detection.cpp
@@ -0,0 +1,94 @@
+#include <iostream>
+
+#include <seqan3/alphabet/cigar/cigar.hpp>
+#include <seqan3/core/debug_stream.hpp>
+#include <seqan3/io/sam_file/input.hpp>
+
+#include "iGenVar.hpp"
+#include "variant_detection/bam_functions.hpp"          // check the sam flags
+#include "variant_detection/snp_indel_detection.hpp"    // detect_snp_and_indel
+
+void detect_snp_and_indel(std::filesystem::path const & reads_filename)
+{
+    // Get the header information and set the necessary fields.
+    using sam_fields = seqan3::fields<seqan3::field::flag,       // 2: FLAG
+                                      seqan3::field::ref_id,     // 3: RNAME
+                                      seqan3::field::ref_offset, // 4: POS
+                                      seqan3::field::mapq,       // 5: MAPQ
+                                      seqan3::field::cigar>;     // 6: CIGAR
+
+    seqan3::sam_file_input reads_file{reads_filename, sam_fields{}};
+    auto const & header = reads_file.header();
+
+    // Check that the file is sorted.
+    if (header.sorting != "coordinate")
+        throw seqan3::format_error{"ERROR: Input file must be sorted by coordinate (e.g. samtools sort)"};
+
+    // Prepare one activity vector per reference sequence.
+    std::vector<std::vector<unsigned>> activity{};
+    activity.resize(header.ref_id_info.size()); // allocate the number of reference sequences
+    for (size_t idx = 0; idx < activity.size(); ++idx)
+        activity[idx].resize(std::get<0>(header.ref_id_info[idx])); // allocate the length of the reference sequence
+
+    for (auto && record : reads_file)
+    {
+        seqan3::sam_flag const flag = record.flag();                            // 2: FLAG
+        int32_t const ref_id        = record.reference_id().value_or(-1);       // 3: RNAME
+        int32_t ref_pos             = record.reference_position().value_or(-1); // 4: POS
+
+        // Skip reads with certain properties.
+        if (hasFlagUnmapped(flag) ||
+            hasFlagSecondary(flag) ||
+            hasFlagDuplicate(flag) ||
+            record.mapping_quality() < 20 ||
+            ref_id < 0 ||
+            ref_pos < 0)
+        {
+            continue;
+        }
+
+        // Track the current position within the read.
+        unsigned read_pos = 0;
+
+        // Step through the CIGAR string.
+        for (auto && [length, operation] : record.cigar_sequence())
+        {
+            // Skip long variants.
+            if (length >= 30) // TODO: use min_length parameter
+            {
+                read_pos += length;
+                ref_pos += length;
+                continue;
+            }
+
+            // Case distinction for cigar elements.
+            seqan3::cigar::operation const op = operation;
+            switch (op.to_char())
+            {
+                case 'I':
+                case 'S': // insertion or soft clip
+                {
+                    activity[ref_id][ref_pos] += length;
+                    read_pos += length;
+                    break;
+                }
+                case 'D': // deletion
+                {
+                    for (unsigned idx = 0; idx < length; ++idx)
+                        ++activity[ref_id][ref_pos + idx];
+                    ref_pos += length;
+                    break;
+                }
+                default: // match or mismatch
+                { // TODO: ATTENTION, mismatches are currently ignored and should still be verified with the reference
+                    ref_pos += length;
+                    read_pos += length;
+                }
+            }
+        }
+    }
+
+    // Print the raw activity profiles.
+    for (auto const & av : activity)
+        seqan3::debug_stream << av << std::endl;
+}
diff --git a/src/variant_detection/variant_detection.cpp b/src/variant_detection/variant_detection.cpp
index 74dd9986..f46c52e5 100644
--- a/src/variant_detection/variant_detection.cpp
+++ b/src/variant_detection/variant_detection.cpp
@@ -53,8 +53,6 @@ void detect_junctions_in_short_reads_sam_file(std::vector<Junction> & junctions,
                                      seqan3::field::ref_offset, // 4: POS
                                      seqan3::field::mapq>;      // 5: MAPQ
 
-    // Set number of decompression threads
-    seqan3::contrib::bgzf_thread_count = args.threads;
     seqan3::sam_file_input alignment_short_reads_file{args.alignment_short_reads_file_path, my_fields{}};
 
     std::deque<std::string> const ref_ids = read_header_information(alignment_short_reads_file, references_lengths);
@@ -115,8 +113,6 @@ void detect_junctions_in_long_reads_sam_file(std::vector<Junction> & junctions,
                                      seqan3::field::seq,        // 10:SEQ
                                      seqan3::field::tags>;
 
-    // Set number of decompression threads
-    seqan3::contrib::bgzf_thread_count = args.threads;
     seqan3::sam_file_input alignment_long_reads_file{args.alignment_long_reads_file_path, my_fields{}};
 
     std::deque<std::string> const ref_ids = read_header_information(alignment_long_reads_file, references_lengths);